Many museums like government archives only hold 2D artifacts, and 3D artifacts are often discarded. Its best in my opinion to find them a home like a regimental museum, and ensure they are entered in catalogue, so they don't wander to private collectors. You can also to a temp/long term loan to them, this way they might be looked after better.
I have done volunteer work for the Saskatchewan Military Museum out of Regina who totally keep everything they recieve, where as the Saskatachewn Provincial Archives only keep 2D items. Many WW1 items from the late COL Don Scott-Calder (who died in Regina in 1979 or the early 80's) were sent to the Archives, WW1 German gasmasks etc, along with documents. The 3D items were not held and were thrown away! Sadly a huge loss to 28th Battalion Regimental history was lost forever. At that time there was no provison for any of these things to be stored. They had been in a box in the RRR officers mess upstairs in the Regina Armouries, not secured, and who knows what went missing. At least if things were pinched, they are still around and not in a garbage dump.
Just be careful of who you donate stuff to, and most importanly ask all the right questions (write them down) about what happens to them, and ask a person of authority, like the curator, not some volunteer at the reception desk.
Regards,
OWDU
