Retractable Rosin Case

This is a rosin case that extends and retracts the rosin using a screw. It is suitable for Hill rosin that comes attached to a piece of fabric with an elastic band. I would often drop my rosin or knock it off the table, invariably damaging the rosin - until I made this case,

You will need:

• A machine screw, #8x24 or #8x32, 1 1/2" long;
• Two #8 nuts;
• A #8 brass insert matching the thread count for the screw you're using (I used these);
• A reamer;
• Some Loctite Threadlocker or JB-Weld;
• Some adhesive for plastic (I used SciGrip #16);
• A hot glue gun.

After printing the parts, assemble everything using these steps:

• Insert one #8 nut into the hex-shaped recess in the 3D printed plastic nut.
• Insert the screw into the plastic nut from the other side, and screw in all the way until it's tight. If you want you can apply Loctite to the #8 nut, but it's probably not necessary.
• Ream the hole in the body to a size suitable for your brass insert. The hole is designed to be small so you can ream it to an exact fit. If you don't want to use a brass insert, alternatively you can tweak the design to make the hole even smaller, and then tap it to accept your screw threads.
• Tap in the brass insert, gluing if desired.
• Insert the screw through the brass insert from the bottom, and screw it all the way.
• Insert the screw through the plate bottom, with the larger round opening pointed up.
• Put a second nut on the end of the screw, tightening until it is flush with the end of the screw. Apply Loctite or JB-Weld to this joint to make sure the nut does not loosen. The nut (and screw) should be able to turn freely in its recess however.
• Glue the plate top to the plate bottom, enclosing the nut. The bumps on the plate top should be pointing up.
• Let the glued components, Loctite and/or JB-Weld dry.
• For Hill rosin, cut off the fabric around the rosin at the base. Hot glue the rosin (with remaining fabric attached) to the plate top.

That's it! Now you can use the plastic nut at the bottom to extend and retract the rosin. Retract it and use the provided cover between uses.