>>8368513One straightforward option is to put up a high quality image of your background of choice on a screen. Play a bit with your f-stop so that it's not in sharp focus (you probably want that anyway when doing toy macro) and it can look okay.
The main caveat here is that your background is going to become a light source when it otherwise might not be, so just take that into account too and light the subject to compensate (or just lean into it like this pic).
