It feels smooth.

It smells good.

And, hey, I can push it! When I do, a little bright spot in the center of the button lights up, and stays so for 25 minutes.

It’s gotta be the most complicated Pomodoro timer ever built by human kind, but it was a hell of a ride.


It’s made of these components:


Here’s my very arguable motivation to build such a complicated thing for so little return:


And these the requirements:


The ability to be charged safely and monitor the state of charge quickly drove me to the rather nice SparkFun Battery Babysitter module, that does everything one needs. Because of the limited voltage of a single-cell LiPo battery, the choice of the Arduino is limited to 3.3V. Finally, because of size requirements, large boards were out of the discussion, so I was left with an Arduino Pro Mini 3.3V and a separate USB module, from Adafruit.

The design of the object quickly converged to a wooden octagon, simple enough to build by hand. I used a table saw to make the external shape. Then I made a circular hole using a router attached to a jig made on purpose to rotate the router along the proper circular path. Then I carved the inside using a drill and finished it with the router. The wood was then finished using oil.

Packing the electronic components inside the wooden case was more of a challenge. It took several hours of modeling using OpenSCAD, to make a parametric design that I could tweak and think through as I went. I ended up writing about 600 lines of code to get this:


I the used the Ultimark II 3D printer to print the holding structure, which I fixed into place using screws a bit of glue.

Ok. Now that I have my timer, I can finally go back to work! 🙂