Jeff is correct. There's a part in Antichamber after you get the second gun where you are supposed to learn a skill but it's not very clear and easy to miss:
.Creating a square of bits fills in the square, creating more bits you can use.
True, but allot of things in Antichamber aren't clear and they aren't meant to be clear. You need to figure it out. And let's be honest, you can totally do that in a reasonable time frame. It's not like you can mess around for hours with different things. If you focus on the stuff you need to know, you can figure it out pretty quickly.
I figured that particular part out in a minute after getting that tool.
When I first used it to create a box of cubes (like the tutorial said I might add), I noticed I still had cubes left even though I painted a wall full of them. Didn't make sense to me, so I made another box, same deal. Ejected all cubes, absorbed 4, created a box and there we go. Allot more than 4 came out. Not hard to figure out, if you look at how many cubes you have you'll probably notice it.