OK so I've found a lot of stuff with clipping through walls and barriers. I'm posting all the notes and such that I have so far.

The way clipping works is to put yourself in a corner, draw a triangle that would create a space too small for you to occupy and then quicksave+quickload. Doing QS/QL solidifies the triangle when it shouldn't be possible to (because you'd be blocking the way of it). Then you draw two points of a triangle under you and bring the third upwards and things should/might happen. The yellow teleportation cube in Ch 14 can be used instead of QS/QL (and is how I originally discovered how to clip).

Clipping with the cube:
Clipping with QS/QL:

Today I spent a few hours testing clipping and oob strats in Chapters 5 through 12. I found quite a bit of stuff so far. The VOD is here: (It looks like the first few minutes are missing but there isn't anything important there).

These are all the notes I took during that stream:

ch 5
-after 2nd statue, clip thru yellow wall instead of flip switch
--can launch up or clip oob into pillar, unsure if thru barrier is possible
-clip thru gate to 3rd statue instead of doing crate buttons
--have to clip into and out of
--vod 2:50

ch 6
-clip down thru barrier at start
--probably not possible. Clipping thru flush surface is hard and not much space to do it.
-clip thru yellow barrier by monk instead of hitting switch (starts ~10:40)
--can get halfway thru
--completely oob
---there's a second barrier before the first statue (~25:00)
-after first statue, clip thru bar gate
--probably not possible, definitely not faster
-gate before third statue in cylinder room is probably too flush to wall to get thru
-clip thru button puzzle rotating wall (starts ~34:30)
--can get stuck between rotating pieces and solid wall
--can get thru wall with multiple clips

ch 7
-no clips to do for first statue
-clip thru barrier after second statue
--vod 42:50
--definitely not faster but silly&fun
-no clips to do for third statue

ch 8
-no clips for first statue
--unless you oculd clip straight down through the floor
-no clips for second or third statues

ch 9
-clip down thru floor of first crystal room into altar room
--vod 50:40
--trapped in altar room, can only escape via clipping
---can clip thru gate you usually enter room via (vod 53:00)
-have to do all light beams on the way to 2nd statue, need them to open door to third statue.
--definitely cna't clip through door to third statue; door is flush with wood walls

ch 10
-might be able to clip thru gate near beginning to get the bonus statue w/o having to bounce light beam
-clip straight thru door to bending light upgrade?
--vod 1:12:00
---if you're oob and qs/ql, it will spit you back in-bounds
-first statue
--probably no clips unless you could get oob somewhere around that room and then get back inbounds.
--would need to still put two triangles by the crystal wheel so you don't get stranded on exit of statue room
-second statue
--clip thru gates on way to timed crystal
--same gates as at 3rd statue, should be possible
---definitely slower than getting thru normally
--last double gate beofre crystal
---vod 1:32:30
-clip thru gate to third statue
--vod 1:19:30
--have to clip into and out of
-clip thru gate to altar
--same type of door as in front of 3rd statue except horizontal bars instead of veritcal. should be possible?

ch 11
-1st statue
--clip thru red bars at very start to skip bouncing light beam around a lot (vod 1:40:00)
---possible to clip down thru the level, go oob. this respawns you on other side with bonus statue+red lasers
--in rotating crystal room, maybe clip through ceiling to skip it?
---clipping oob and voiding out is possible. doorway might be too thick/solid to clip thru tho. very awkward angle to work at
-2nd statue
--can't clip directly to statue, all nearby surfaces are wood
--clipping thru red exploding boxes causes oob falling thru world and voiding out
---vod 1:56:30
--collecting bonus statue from oob vod 2:05:40
---can go oob and walk on top of explosive boxes but isn't useful (can't place triangles on boxes)
-3rd statue
--statue can be collected from front (vod 2:13:20)
---can just lean thru glass or clip through completely
-at 1st or 2nd statue, can clip thru wood bars where you place top triangles (vod 2:18:30)
--probably a proper strat to easy block red laser and get back down to go to next statue
--can also go straight to altar form there
-fun wiht a bonus statue (vod 2:21:45)

ch 12
-all 3 statues are right at start at altar, only yellow light walls blocking. should be able to clip to each of them
-collect a statue from oob (vod 2:23:50)
-collect another statue from oob (vod 2:28:30)
--have to clip/oob back out or do intended strats for this statue. noramlly you lower this yellow forcefield and then go through the hole in the wall ot the next one
--getting back inbounds (2:36:50)
--playing with the fox ghost (2:35:30)
-got to third statue, but i'm an idiot and vod is black at that part 🙁
--2:49:15 got thru a second time

ch 13
-very few walls, unlikely to have many clips
-first two statues probably intended strats
-third statue may be able to skip bouncing light beam and clip thru games
--would require 2 clips for 2 gates
---tested this some a few days ago, did not go well (triangles randomly disappearing while trying to clip, very strange)

I'm going to do more testing on the last few chapters soon and will post about those soon.

Chapters 14, 15 and 16.

Ch 14 was already broken a while ago so I didn't do much there. The other two don't have a whole lot where clipping would be beneficial (probably).

VOD:

Notes:
ch 14
-clips already used to get two statues. new qs/ql strats are much faster than yellow cube strats
-THEORETICALLY you can use one of the crates to box jump up to the island above the main section of the level to skip the puzzles and collect third statue
--this is incredibly difficult and I've only been able to get up to the top of the shorter smokestack
-maybe clip thru yellow barrier instead of throwing teleport cube through?
--not much space to work with
-clipping through the orb around the altar is the ultimate dream as this would skip Laser Hallway
--you can throw the yellow teleport cube to get on top of the orb but you can't place any triangles there

ch 15
-square hole planet statue
--nothing to clip thru or into
--might be possible to box jump up to the statue?
---gravity in the room seems stronger than normal for you+boxes, can't get more than two box jumps off the ground
-ghost cube statue
--nothing to clip thru or into, just have to do normally
-white laser statue
--clip thru yellow glass at start to get right into Cylinder Room?
---14:30 what the heck
--can use blue cube instead of crate to block red laser
---easier and less frustrating, but possibly slower if you get crate strats quickly
---21:20
-clip through the yellow barrier to get to altar and skip Split Kami puzzle?
--video of theory+testing already on yt

ch 16
-could you clip through the invisible floor to fall down to where the fox is? probably not and definitely not useful
-clip thru yellow barriers at start to skip guiding the fox
--25:30
--definitely possible (~30:00). only need to oob once to get past both barriers
-circle room
--clip thru the gate(start 33:00)
--seems like it should be easy but isn't
---second gate is same style as first gate so clipping thru first would be faster (so you don't have to block the laser)
--can clip oob then void out and it resets you to final puzzle room!
---vod ~40:00
-final room
--can clip oob in final room (49:00)
--can clip thru glass to hang out with the red fox (51:00)
--might be able to go far up the wall and clip out and land on a platform then go the final altar/portal.
---since it requires two switches to be pressed to spawn the portal, this probably isn't useful

wow, this is awesome! Nice work!

Ok have done a lot more messing around and have a route figured out. Here's more notes plus a VOD of a rough Any% run. My Any% Sum of Best is down to 1:20:20 so I think a 1:15 is pretty plausible if everything goes mostly smooth. Bending Light should be able to save at least a minute in Ch 10 but not much anywhere else since there aren't many useful clipping strats in the first ten levels.

General Notes
-Putting a tri flat on the ground where you're going to clip seems to reduce the amount the camera jitters around making placing tris much easier. This helps to make clips more consistent
-Always stay crouched when setting up. When you uncrouch it's very likely the game will spit you out through the triangle you blocked yourself in with.

CH 1 thru 4
-Ability to walk on walls seems necessary to clip. Probably can't clip in these levels.

CH 5
-3rd Statue Clip Time Testing
--Clip thru gate
---37.84s
---37.95s
---41.75s
--Do Box Stuff
---29.39s
-regular box stuff is faster than clipping (probably) 🙁

CH 6
-doubtful that any clips in this level are faster

CH 7
-no useful clip strats

CH 8
-no useful clip strats

CH 9
-no useful clip strats

CH 10
-For Bending Light%, clipping thru door to upgrade reduces level to under a minute (less than 45 seconds if you get the clip quickly)
-For Any%, can clip thru gates before third statue and before altar. Not sure if faster than doing fast reflects

CH 11
-Instead of getting thru red bars, easier to clip in corner next to red bars. If you void out you are reset behind the red lasers next to the bonus statue. If you don't void out you can just jump across to that area.
-chapter routing
--clip thru wall to skip initial light reflection puzzles
--rotating crystal still needs to be done (intended strats)
--red exploding crates can be skipped
--clipping thru bars at top of either rotating crystal or red boxes makes blocking red laser much easier+faster
---from here you can go straight to the altar (hidden blocks in corner near rotating crystal puzzle)
---maybe do laser+acid room statue first or second instead of third and then clip thru small bars at top of one of the other puzzles to skip having to block the red laser and go thru the box/door puzzle

CH 12
-Can get all three statues via clipping without solving any puzzles
--need to get good videos for this

Ch 13
-Third statue
--It is possible to clip OOB and go around the two gates to grab the statue
---Have to be careful not to put a tri on or thru the wood of the gates or the tri auto-deletes itself
--Consistent reflect strats are probably faster

Ch 14
-Clips to first and second statues are even faster with QS/QL
--Second statue you can clip back out of room instead of putting critter on button
-Third statue and getting to altar are probably just using intended strats
-Third statue you can clip in red laser room to go OOB and get straight to teleport
--can't clip thru gate in box room (flush to wall, half of wall is wood)

Ch 15
-No useful clips for any statues
-Might be able to clip thru barriers to get to altar without doing Split Kami puzzle?
--can clip down thru the floor into the split kami room

Ch 16
-Go OOB and void out at very start of level (vod 46:00)
--voidng out resets you to final puzzle room
---if you launch too far away from the rest of the level it can reset you back to beginning of level. For safer voiding, can be done at yellow barriers
--no way to skip final puzzle

ROUTE SO FAR
Ch1
-box jump over invis wall, finish level
Ch2
-regular intended strats
Ch3
-regular intended strats
--possibly jump strats to get third statue first
Ch4
-regular intended strats
Ch5
-regular intended strats
--can do clip strats for third statue for swag
Ch6
-regular intended strats
Ch7
-regular intended strats
Ch8
-regular intended strats
Ch9
-regular intended strats
Ch10
-For Bending Light:
--Clip thru door to upgrade
-For Any%:
--Most intended strats
--Can clip thru gate at third statue and gate at altar instead of reflecting
Ch11
-clip at start to skip starting light reflects
-do Rotating Crystal room, leave w/o placing tri up top
-go to laser+acid statue, clip thru gate to grab without going around
-go to Red Box room, clip thru wall and climb up to statue
-go to wood bars and clip thru, use hidden blocks to get to altar
Ch12
-do clips to get statues without doing any puzzles yay
Ch13
-intended strats all the way
--maybe clip oob at third statue to skip gates, but probably not faster than good reflections
Ch14
-clip to get first and second statue fast
-use yellow cube to go down to start of third statue area
-clip to skip first puzzle then do box room and grab statue
-do laser hallway and go to altar
Ch15
-Mostly intended strats
--for White Laser statue, can use blue cube instead of crate to block red laser
Ch16
-Go oob and skip to last room
-do last room
Ch17
-donesies