Sometime in 2014 I read about this toy first. I didn't like the resistor solution. So, I was thinking, how to replace it with something new. And I was thinking, that the 12+4 places are a little few for my taste. I thought, I would add more places for the blocks. I felt the 4pc subroutine was too small, and just one subroutine was too little also.
The magnets came to an idea, but then I calculated, how many of them I will need, multiplied it with the cheapest source of HAL sensors, and I knew, they are out of my budget. Back to the drawing board. I couldn't find any solution, what did not required an electrical connection, and the same time it's costs wouldn't be prohibitory. OK, then it's going to have connections, but as little, as it is possible.
I came to idea of using 1-wire EEPROMs. Using it with only two wires (data+gnd) looked good. The V1 resistor solution had also two contacts, so it looked feasible. Search for the 1-wire EEPROMs gave price in the same range as HAL sensors. OK, so this is dead-end. I really don't know, why are those that expensive. For the price of 1pc of 1-wire EEPROM, I could buy a dozen of I2C EEPROMs, at least.
For the I2C EEPROM, there is at least 4 contacts to make. So I started to search for the solution to make those contacts fairly stable. I wanted something with a spring in it, to have a good contact. And then was an article about pogo pins, and it was like, that was the thing I was searching for. Ok, I have it, now source it somewhere. I ended up purchasing 3 packs of 50 pieces of it, off the ebay.
They looks like this: