I've never been into tops, but after seeing the high-tech tops on the Internet costing upwards of $1000, it brings new interest for high-tech kid toys.

This top was designed after designing and making some roller-nearing spinner toys for my daughter. This top is the next thing.

Tops that wobble and turn about 20 times and fall are no fun. Correct me if I'm mistaken but the key to a long-spinning top is stability. We're not talking about a $1000 top that is CNC turned on a lathe but 3D printed from plastic, where is hardly any weight, so stability comes with added weights. The heavier the weights are, the more momentum it will have. Keeping the weight low will lower the center of gravity which improves stability.

This top was designed to take 6 3/8" nuts, and a 1/4" ball bearing on the bottom.
The key to this top is balancing the nuts to keep weight as evenly distributed as possible. Each nut varies slightly in size and weight so it's important to weigh them individually.

Obviously, the higher the precision, the nicer the part will turn out. I would recommend using a standard PLA, since pressing the nuts into the top may crack it. Don't ask me how I know this. This is the second one I've printed, with transparent aqua PLA. The previous top I've printed was a standard PLA and turned out great, without cracking. Perhaps soaking the top in hot water before pressing may help softening the PLA, but when the plastic cools, it might crack under stress. I haven't tried it - just a suggestion.

I printed my tops with 3 shells and 15% infill, but it doesn't matter too much.

Enjoy.