Smalle clothespin like clip for mounting on a 25mm "diameter" tube. With a small eye to attach other things.
Use at least 5mm outer/4mm inner 0.8mm springs or bigger. 15/20mm length
7.5/6/5/0.7x20 still fits and is quite strong
Use m3x8 bold as shaft (without nut is possible)
Scale for other dimensions
Print both sides in one print.