Thumbling

This is a toy that keeps your thumb and fingers agile and gives you something to do when you have nothing to do or are waiting for something to happen (e.g. watching tv, participating in a video call, waiting at the bus stop, shopping in a mall ...). The operation is simple: you take the thumbling in the hand and move the handle or handles around with your thumb or the fingers. It is really pointless, but for me it is big fun :)

You can print it in different sizes and shapes. Geometrically it is simply a cube with a ball inside that has a torus as handle. The measurement that defines the size is the length of a side of the cube. For me sizes between 30mm and 40mm work best. What works best for you depends on the size of your hand and your agility. There are no sharp edges or corners so that it lays very comfortable in the hand.

The path for the handle is defined by the edges that are cut of from the cube. For the twelve edges there are 4096 combinations of removing them. But only 1082 variations will result in a cube where all corners are connected and only 38 variations remain if you eliminate the variations that can be transformed to each other by rotating or mirroring.

I included 17 variations in the openscad-file that you can choose from and gave them names that somehow represent the shape of the result.

The sticktype to create the handle on the ball can be one of "single", "edge" or "across". "single" will create one handle, "edge" will create two handles at 90 degrees and "across" will create also two handles but on opposite sides of the ball. "single" gives you the most freedom of movement, but "edge" is also very fun to play with. There are not many variations that work for "across".

It is also possible to print a "holder". This is a holder in which a thumbling can be placed and that can be clamped to a round bar, e.g. at shopping carts. So you can play around while going shopping.

The STL-Files are named using size-sticktype-bodyshape.stl.

For me it works best to print this with PETG, since on the one hand the printing result is very smooth and on the other hand it is so stable that dropping it to a hard surface will (hopefully) not harm it. Dropping it with speed will harm it anyway ^^ PLA will break easier and TPU is not useful because the cube needs to be rigid to be working smoothly.

The holder must be printed with TPU. It needs to be flexible to allow the thumbling to slip in and to clamp around the bar.

When arranging the model on the printbed it is best to make sure that corners with only one edge connected are pointing up or to the side. When pointing down the edge may print suboptimal. I always print the thumbling with supports. After printing the supports must be removed. Most of them come off very easy, the rest can be removed using a box cutter or something similar. The shapes in the openscad-file are arranged for best printing results.