One easy way to make guages is just to take the retaining rings from canning jars and then just print guages from pictures online and size them to fit the jar lids. Soda bottle tops make good knobs.
I covered mine in foam sheets so it looks like a crypt using magnets to hold it to the door. If you cut out plastic in the shape of the slime trails you could lay it out on the door. However remember as the door opens the surface area increases because of the gaps between the panels so you will need some method to hold it in place that accounts for the movement.
How about these. They have space under the surface to allow water to drain from underneath if place on a concrete pad. That space would also be perfect for electrical chords and since they interlock it should create a fairly flat surface.
Married with no children. Long time horror movie fan
Flying, chess and halloween
My love, sweet Queen and noble wife. I alone remain to bring delivery of your pain. Severed my darling, too quickly from this life. Of fires drawn and memories met, I shall hold our two hearts again in single time.