Tube Squeezer

To use line up the slot on the shell and nut and slide the end of a tube so the end slightly sticks out of the bolt. Then untighten the nut, slide the bolt out about 1 mm and rotate it to squeeze the tube. To lock it in place slide the bolt back in and tighten the nut.

If your printer isn't super dialed in threads might be an issue. Threads might be rough off the printer but after some use they get smooth.

Edit: Rounded the corners on the shell to make it stronger.

Happy printing!