I modeled and began 3D printing these because I was tired of purchasing modern friction pegs for vintage banjoleles and ukuleles that I was restoring when the buttons were cracked or completely destroyed (I've even had some of those old bakelite ones crumble under the smallest amount of tension). I realized I had a decent little stockpile of champion junior hardware, but no buttons. 

I've modeled these to be slightly wider in the concave portion of the button because those are a week spot for the old bakelite ones. 

I have tested and have been using these on a Le Domino Soprano for quite some time now. They are incredibly strong, certainly stronger than originals. 

These buttons have been printed completely solid with pla+ so they can be sanded and polished, should you want an even smoother finish. 

I will test fit each one before I ship them out to make sure they fit on your champion jr hardware. That is, hardware that has a 2.6mm wide square post. 

I just want to reiterate that what you are buying is 4 of the plastic buttons, without hardware. I'm currently making these in White, Vintage White (a very close approximation to aged celluloid binding on vintage instruments), and black. Check out my other listings for these. Should you like to purchase sets in a different color, please let me know.  

*The last photo is simply to show you the type of hardware you will need with these buttons. Hardware (the metal bits) will not be included.