9. (Occasionally Sonic) Screwdriver
If classic American sci-fi indulged in a spot of cheapskate corner cutting, then that counts double for the Brits who made "make do and mend" their whole mantra. Even the big hitters of 60s British TV sci-fi, like the BBC's Doctor Who or ITV's "Supermarionation" shows (Thunderbirds, Captain Scarlet etc.), extensively reused their own props and sets. Despite being on different networks (and the puppet shows being at a different scale to ones with real people), they even shared each other's materials.
This was the case for even the signature prop of the most iconic British sci-fi hero of all: The Doctor's sonic screwdriver.
At the turn of the 70s the BBC acquired a bunch of old Supermarionation props and quickly turned them to use on its sci-fi flagship. Third Doctor Jon Pertwee was given a new sonic that had already made an appearance as a plain old, non-sonic, screwdriver in the feature length Thunderbirds Are Go. Fortunately, Pertwee didn't have to deal with a tiny, puppet-sized screwdriver as this one was specifically used for the close ups in Thunderbirds, in which full size hand actors were used.
To make the prop look a little more "sonic" and a little less like a basic screwdriver an antenna was added. This too had had a past life, in this case as Captain Blue's communicator on Captain Scarlet, making the finished sonic a mash-up prop of multiple Supermarionation pieces.
In more recent times, the revived Doctor Who series took to using a commercially available licensed replica of the Ninth Doctor's screwdriver for some scenes as it was more robust than the real prop!