This is a basic handle for a speed rope, using 608zz bearings. I chose this size as they are commonly ordered in bulk for other projects. As such, I myself had a dozen or so extra lying around. If you don't already have the bearings, it's probably more economical to just buy an inexpensive speed rope than to order the bearings and cable for this project.
I have printed this out, assembled it and used it a number of times, although it is not my go-to jump rope. I don't love the handle size and shape, so that might be modified in a future iteration, but it does have excellent spin. It has held up to a dozen or so sessions of single and double unders of up to 15-20 minutes.
This makes a very smoothly spinning speed rope. Print the parts complete if you dare. They have very little clearance, so you might want to scale up the outer handle slightly to allow the innards to slide in while remaining snug enough to glue into place.
I printed the handle parts in halves, out of PLA, and assembled it with super glue in this order:
If printing out the parts complete, instead of as halves, the bearings assembled on the pivot can be slid into the outer handle from the open end.
Rafts:
Doesn't Matter
Supports:
Doesn't Matter
Resolution:
.2
Infill:
20%