Adapters for retrofitting a window to an old computer case. You need four corner pieces, and a set of side pieces (I printed four). The clamp slides over the metal lip that computer cases have, and it is fastened to the case using threaded inserts and screws. The window then slides into the larger grooves.

The OpenScad file is included, in case you need to make adjustments. Print with supports (which are a PITA to remove).