Glad to see you made it over to ECN, Albert. Welcome aboard!
These days when mention is made of "computer," most people automatically think of a modern digital computer, forgetting that a whole range of analog computers were used for all sorts of problem-solving in the past.
One of the British electronics journals Practical Electronics
, if I recall correctly) ran a constructional project for a general-purpose analog computer in the late 1960s/very early 1970s. Of course, by that time with operational amplifiers available in the form of integrated circuits (e.g. the ubiquitous 709) it had become feasible as a home project when to have built such a thing as a hobby project a few years earlier with hundreds of triode tubes would have been out of the question.