Catacombs Model Gallery
Microscope

Maya's microscope in Seed Of Destruction was made from Osma brand plastic plumbing pipes, just like the Space Warp detector a couple of episodes later. The eye-pieces are made of Osma-T37 bends with with 2.5 inch sockets.

It also makes a brief appearance in the background in The Beta Cloud

It's in the Records Lab in The Bringers Of Wonder part 1, and is thrown across the room (revealing the hollow base).

It's also in The Lambda Factor (alongside the Space Warp detector, in the foreground).

In The Seance Spectre and Dorzak it is in Command Center

Again alongside the Space Warp detector, another version of the prop appears in The Immunity Syndrome. It has no top section, or decoration.