I think the project is great. I got the lid in a 1x1 and it works fine. However, I had to make a small adjustment because one of the tolerances is too tight. I tried it with the Perplexinglabs box (Gridfinity Extended) and I also designed a small test piece following the Gridfinity specifications and got the same result. The rail height was 1.2 for both. The problem is that the first layer of 1.8mm has no tolerance (almos 0mm) with respect to the lip. I gave 0.1mm of tolerance and although it still a bit tight, it could be opened barehands with a little force. In photos you can see before and after. Thank you

It works incredibly well, you can tell it's a very well-designed product. The only thing is that the blade guide can rub if you don't tighten the top part that fits onto the blade properly.