This is a damper that goes on the top front frame of The 100 DIY 3d printer. I designed it to be used on my Spartin mod for the printer that increases the vertical build area to over 350mm. But it should work on the standard printer as well.

The issue this is trying to address is that the printed frame of the printer is not very rigid. When you start cranking up the printing speed, even on the normal sized printer, you can see it flex and spring back causing a vibration.

On my printer, I filled this with lead shot, but other substances might work as well. The idea is to make a "dead blow" hammer effect, and lead shot has long been used to do this. I haven't tried it, but sand might work as well. Whatever you use, make sure it has the ability to flow and move around. This mean, use the finest, highest number shot you can get. Maybe even a silicon fluid would work. You don't want to add a solid weight because this does not have a damping effect. Also, the more weight you add, the lower your max acceleration will be. Use your resonance tester to find the best solution.

Install this in place of the top front connector.