This is a spatula I designed for fun that has interchangeable blades that click into place and can be released with a lever.
The standard blade has two usable sides, so it can just be turned around when one side goes dull. All other blades are more specialized and have only one functioning side. The most specialized version is the wavy blade that needs to be printed in a special orientation for it to be usable in a meaningful way. All tolerances are chosen for FDM printing.
I wanted to also design an adapter for standard razor blades but have gotten too lazy. If someone else would like to do so I'd be happy to help, though.
Be aware that the supports will need to be removed! Place support blockers in the appropriate locations for this to be possible or use custom supports.