Quoted from Jeremy8419:But like $150 for the main kit materials, a few hundred more for the playfield parts, usb cords, a few hundred more for the control box, a free app, a couple days on the weekend to assemble, and you have your own custom pinball machine
The P-Roc and P3-Roc hardware are really as close as you're going to get to that, for now anyways. The P3 platform with customizable slide-in assemblies and a rear module that you can customize on a work bench, plus an open software developer kit sounds pretty close to what you're asking for as well, or at least the closest that actually exists at this time. In the future, who knows?
USB sounds friendly but realistically it probably isn't going to work in an environment with any kind of EM interference and suffers from latency and addressing issues. 10 or 20 USB cables going back to some kind of hub sounds no bueno to me. No matter what you do you're also still going to need to deal with power supplies and driver circuits too, so you're back to these "analog wires".