Any use for otherwise junk items would be fine, but I was thinking more along the lines of existing facilities. Currently the improved lab requires elerium and alloys, and the advanced lab requires elerium as well as power sources and navigation. Given how plentiful elerium is and what other uses it already has this seems a bit redundant, especially for the advanced lab (as elerium is already used for constructing power sources), and both navigation and power sources already have other uses. It's also not quite clear to me what purpose all that raw elerium serves.
I think alien multitools and alloy welders might be of better use, given that we are working with alien tech. Lore-wise, trying to reverse-engineer this tech might be a lot easier if X-COM had the tools used to maintain said tech, wouldn't it? The sensorium (and PSI amp as far as items are concernded) is another example where the building materials approximately match the in-game lore/use of the facility. None of these materials are really all that rare to impact player progression, but they add a lore-friendly use for them to make them more than junk items. Large workshops / Tritanium Matrix might be additional facilities that might make use of alloy welders.
