Use a 3M metric machine screw with washer through this, and then through one of the custom middle sections. Add a washer and a nut and tighten the two parts together. (If they're loose, it won't spin well -- if at all.) Finally put a dab of hot glue into a tip, stick it onto the bottom of the screw, and let it rip!

For the square pattern, add some weight to the top by attaching screws and washers using the holes. The other design is supposed to be hearts, but it turned out looking more like a four-leaf clover.

These probably won't be the highest performing tops you have, but you'll be the only one who can say you made it yourself. And yes, I know the print quality is awful here -- it was one of our first prints.