ZDoom

I don't think there's a good specific forum to be asking this around, but if you can move it to one, go ahead.

I've been buying cheap toy guns and stuff from yard sales and arcades with the intent of digitizing them. The only really issue is that I can't think of a really practical fashion to do so, especially for one-handed weapons like pistols and knives. Mainly talking about things to hold them up on, how to make my real hands not show up so I can edit things into them, etc.

Camera quality doesn't really matter given the nature of the game we're talking about here.

Camera quality may not matter, but you'll definitely want to ensure that your photographing conditions are as ideal as possible. Have good, consistent lighting; know how to set focus and white balance, and find some way to ensure that the weapon is in the right spot in frame and not moving around too much. Consider things like a vice or weapon bench(? I'm not sure of the exact word) to hold it still. Lastly, background matters. Have a way to ensure that you're not needing to constantly manually trim the background out of your photos. A solid colored bed sheet tacked to a wall could make a decent chroma key screen if you set it up correctly.