When I first moved to London in the late 70s, I took an evening course in making electronic music. Each person had the use of a VCS3 and a Revox. The teacher showed us the basics of these machines, and then just let us get on with it. You were considered to be a wimp if you attached a keyboard to the VCS3 :)
Great fun. Sadly, work got in the way, so I never had time to explore things further. But every now and then I hear something - for example, the other day I was listening to the Orb's live album from the early 90s - that I instantly recognise as a VCS3, very like the sounds that I used to make.
reverb.com currently has an original for sale for £22,000. That includes a keyboard - wimp!