Assuming that this is for a non-SLR camera, if you do mostly black-and-white photography and mainly use one filter, say, a #8 yellow, then you can probably cut what you need from a Kodak gelatin, or Lee acetate filter. These are so thin that they don’t distort the projection in a meaningful way used between the lens and film.
These can be affixed onto the rear of the lens barrel with tape. Also, you might make a simple version of a Xenopon Beak rear mount holder (secured with tape). Cardstock or heavy paper is a likely material. Once installed, you’d simply leave it there.
This might not work on an SLR due to the proximity of the reflex mirror, as the snapping motion of the mirror might induce enough air turbulence in the mirror box to dislodge the filter.