I loved my Kosmos electronics kits. My mom threw out the kits eventually but I still have the manuals.

https://patric-sokoll.de/SonstigeSammlungen/Kosmos%20E200/Ha...

My first computer was their CP1. It was aimed at older children and teens. You programmed it in a custom assembly language. The manual included lots of projects and instructions on how to hook it up to their electronics kits.

http://www.8bit-homecomputermuseum.at/computer/kosmos_comput...

http://www.8bit-homecomputermuseum.at/computer/pictures/kosm...