The assembly took longer than expected, but now the complete system works as it should. Main hindrances to completion were, aside procrastinstion, apperent lack of time due to personal life issues, and -- bigger problems was mystery short-circuit (remedied by slightly bending the board) and misapplication of epoxy resulted in stuck switches. The latter problem was solved by making and attaching small board with new switches. 

Here is photo of prototype working (photos were made before epoxy misapplication):

I hope in several days I add a video of the thing working. For nearly month I am not going to build new devices because of transistor shortage - a new batch should come in a month, approximately. For now I am going to reevaluate my logic gate design, to see what can be done to make them faster with at least the same reliability. Maybe even use less parts per gate?..