Not house extensions, just computers … so I built my own from scratch. Well, I didn’t exactly get a soldering iron and a bag of computer chips, but I did research what worked well with what, what was required, where to get it and then ordered all the parts and built it. And then I turned it on .. and it’s worked spectacularly to this day. I’m on it right now. It’s a PC of course, you can’t build your own Apple can you?
Or can you? Well, you used to be able to … not so much the logic board and the power supply bits, but you could add all sorts of boards inside, pretty much attach them to anything from a recording studio to a typesetter rip (raster image processor) and tinker inside to your hearts content .. and I’ve done most of them! More here and here ..