Instructables

Step 3:

4. Next, grab the lid to the glass jar.  Put a small hole in the lid using a small drill. It needs to be larger than the shaft of the motor but not much larger.  We want the shaft to spin freely but don't want to leave such a large hole that we will have to leak proof later.

5. Test that the shaft spins freely in the jar lid by applying power while the shaft is in the hole.  Clean the hole and make sure there aren't any metal burrs that will damage the shaft of the motor or the rubber “o-ring” that will be constructed later.