Barbell Collar
thingiverse
Crafted for seamless integration with a 1/4-20 bold and 1/4-20 t-nut assembly. T-nuts were my only available option at the time, but you might be able to modify it to accommodate a threaded insert where the t-nut resides as well, adding extra material to the t-nut allows for even clamping force distribution also.
Download Model from thingiverse
With this file you will be able to print Barbell Collar with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Barbell Collar.