Quad Dome from Electronic Goldmine

Looks like these might be nice for a quad hat; also available in red, if you like that HAL look.  Sales page says:

Green See-Thru Super Quality Acrylic Dome-The Electronic Goldmine:

"These domes make great additions to small robots. They are large enough to mount sensors, small circuit boards, LEDs, lamps, etc. underneath. Each dome is 2.83" in Dia. plus a .5" mounting lip. The highest part of the dome (at the center) is about 1" tall. These were made for large projection TVs and came in to us in sealed master cartons so they are in perfect condition. Green See-Thru.