I was successful building my kit after finding the extra length camera cable. I've scanned a few items already.
I agree that the instructions can be a bit hard to follow. A video would have been very helpful, or at least a few pictures showing parts orientations, etc. ("Front" or "left side" for example without reference to which direction things face can be problematic). I'm not a huge fan of making all of the electronics basically inaccessible as well. I appreciate the look, but you can't verify operation until everything is done. Then, if you have to change anything, you have to dismantle the entire structure. Don't ask me how I know....
The interior size of the holes on the ever-so-slightly rounded square standoffs are different than the not-considered-rounded squares I believe. Otherwise it wouldn't matter which ones you used where (i.e. there is no physical reason that I can see for one being rounded vs not, other than a way to differentiate the two parts with different hole diameters). I believe the square edges are for the standard "D" screws (3mm?) and the rounded edges are for the 2mm or 2.5mm screws for the Pi.
I didn't end up attaching the "T" shaped piece on the back that covers up the laser wires and camera cable. It appeared that it was going to squash the camera cable and I wasn't comfortable doing that for mostly cosmetics. So, I used a couple pieces of tape to hold things fairly neat/tidy and used the shorter bolts to fill the extra set of holds for the laser support pieces.
All in all, I think the kit was pretty decent, but could use some improvement on the instructions. I very much like the single, solid ~1/4" thick piece of acrylic for the shell over printed parts. The completed scanner is very hefty and solid feeling and I think will hold up better than a 3D printed version.