Design an enclosure

[metalcopper]

I am going to be building three new enclosures, all will be 36 in long X 20 inches deep X 20 inches tall, at least that's the plan. I plan on putting in a light fixture on the ceiling, and laminate the floors.

My questions are, in your guys' opinions, should I use a porcelain light fixture, or will plastic work as well?

Should I put anything on the walls, or is the plywood OK?

I plan on making the front door open to the left, rather than a draw-bridge style so they are all the same and the one on the bottom will be easier to clean without the door laying on the ground in front of me while it is open. I've used glass in the past, but is Plexiglas better?

How about heat tape? I've never used it, I don't want to spend too much money on all this, thermostats are not cheap, and how would I install heat tape on these enclosures that likely will be stacked on top each other?

Any other recommendations and advice would be awesome!