The fourth module I created myself is the Tic Toc module. I often annoyed me to use a VCO as a clock, because then I had one missing for creating sounds. The design used in this module is by Circuit Abbey Tick Eurorack Clock Kit. It is a simple 555 Timer circuit which perfectly does the job. I've just added a second output which first is lead over a RC circuit to form some kind of triangle. If I don't need it, I have 2 pulse outputs, which can be perfectly used as a clock module.
I especially like the dog button I've created by my own. It's a childs toy. I've cut off the head, drilled the hole and fixed it with some glue.