Connectors for 3D printer enclosure based on 500x500x2 mm Polystyrene

I want a simple, transparent enclosure without any movable parts (I lift it by hand when I need access) and without interstices (to keep the warmth and the noise in).

My local construction market sells Polystyrene plates (Hornbach, Hobbyglas, art.no. 1477801) with ideal dimensions (500x500x2 mm) for my 3D printer.

Because I have bad experiences with drilling and sawing this material, I leave the plates as they are. The connectors are just tight clamped upon the plates.
A small droplet of PVC-glue on the small connectors may be handy.

The package consists of:

3-plane connectors (at the vertices): you’ll need 4 of the top elements and 4 of the bottom elements.
Note 1. The deepest interior of each corner is enlarged to give a better tolerance toward material surplus or residues.
Note 2. The top elements have small holes to hoist it up from the ceiling. :-)

2-plane connectors: You’ll need 24 long elements and 16 short elements.
Note: in an earlier phase I designed elements as long as possible, but it was awkward to slide them to the right spot during construction.