Here’s a design that lets you make acrylic enclosures without using fasteners. The red outline in the diagram above is a bit hard to make out. But look closely and you’ll realize that there is very little material which has been removed to form the clip. This uses the rigidity/flexibility of the material to form a spring that will hold a couple of pieces tightly together.
In a links post last year we looked at [Patrick Fenner's] fantastic analysis of the strength of using kerf-bending to form several sides of a case out of one piece of material. He’s used that same analytic expertise to take a look into this design. He even suggests that making the cut on the hook-side a bit deeper will help improve the resilience of the part. If you have a laser cutter on hand and want to give this a try he’s posted the plans on Thingiverse.