I built the original Prusa Lack MMU2 enclosure (https://blog.prusa3d.com/mmu2s-printer-enclosure_30215/) and I like it very much, but unfortunately it only provides the possibility to open one side (the front of the enclosure) while the other three sides remain closed. 

I then cut into the bottom parts of the enclosure that hold the acrylic sheets, so it is possible to pull the sheets and slide them out of the upper enclosure parts (see pictures). If you don't want to cut into the parts, you can directly re-print the updated parts here.

This simple closure can be screwed into the sides of the Lack table to secure the side sheets when they are put back. I used 4x20mm Spax screws, but longer ones would also work.