A simplified version of my ECG visualiser. It can be printed without supports (although a raft is advisable). Subsequently, you'll either need toothpicks and glue or bits of the raft and glue to assemble it. Note: it's a little fiddly but manageable.
It's still not the print-in-place-spin-and-voila design that I first imagined it could be. I'll try to keep improving it and maybe it'll get there eventually.
Thank you to downspout, choover and all the other people who commented on the original - you guys inspired me to come back and improve it.