if you own one of these popular (ebay) usb microscopes you may be interested printing an attachment holder to keep everything together.
the holder clips onto the height adjustment shaft and does not impede the movement
design spark (spaceclaim) file attached if anyone wants to modify the fit.

two stl's attached
normal one has the supports already so you dont have to add any
the other file "support required" is without supports so you'll add supports to get the best/strongest print.
you might have to heat the clip a little to get it on without snapping
EDIT: Added a V2 with an extra attachment holder and some small mods, support already included.