This is a solid version of the 3DVerkstan face shield that fills in the tray to support upper layers. With that I was able to add a .6mm gap with several 1mm columns to allow for stacking. I've successfully printed these in stacks of 2, 6 See https://3dverkstan.se/protective-visor/protective-visor-versions/ for further assembly instructions. For CAD/STEP files you can export the model here: https://cad.onshape.com/documents/64e392965af08847ee011fea/w/497b9f93aeea40b20e4a3e5d/e/bf5e2c7583c1dbd70dfdcd97