It might be a bit of work, but you might be able to disguise the round prongs/nubs (whatever they're called) by gluing a big mess of wires and plastic straws over them. You could try weaving the wires between the prongs, or just put a bunch of them running straight across the front. That way you'll have the smooth lower wall, a layer of ceiling-level wires and conduits, and then the shim on top. If you curl the wires at either end of the block, they should look like they're disappearing into the wall when you put two blocks together.
Also, on the mask/respirator issue - I had to do some OSHA (occupational safety & health) training a few years ago and the instructor mentioned that most masks & respirators don't work properly if you have a beard. Just something else to keep in mind when thinking about hobby PPE.
Also, on the mask/respirator issue - I had to do some OSHA (occupational safety & health) training a few years ago and the instructor mentioned that most masks & respirators don't work properly if you have a beard. Just something else to keep in mind when thinking about hobby PPE.