In Part 3 of this build, I’m back on the DIY cardboard laptop mount that bolts onto a VESA arm. At this point I already have the bolts and the plate embedded into the bottom, so now the job is adding the side panels and the inner “stopper” pieces that make the whole thing stiff, clean, and strong. I’m using that double-layer-on-the-edges approach with a single-layer piece that helps lock in a solid 90° connection, and I’m test fitting constantly because cardboard thickness will absolutely mess up your measurements if you don’t compensate for it. I walk through how I measure and cut the side pieces (including fixing my own mistake when I forgot to account for the base thickness), why I switch rulers depending on the job, and how I use hot glue in a way that gives me time to line things up. I also add internal ribs for strength, because this mount needs to handle real use—and I’m planning to fill the stand with sand/dirt to hit the VESA arm’s minimum weight requirement. It’s a chill livestream-style build, but the takeaway is serious: test fit early, plan your build order, and don’t be afraid to iterate when something’s “almost” right.