Reminds me of a fully-analogue approach to generate arbitary waveforms using a cardboard template stuck to the front of an oscilloscope. Basically, cut out the desired shape, stick it on the 'scope and point a photocell at the screen. The photocell drives the Y axis in a feedback loop so the spot height is a function of brightness -the idea being that the spot rides along the top of the template maintaining a constant brightness (with X timebase setting the output frequency - fairly obviously, needs an analogue 'scope with fully variable timebase).

Could probably do it with a flexible curve these days, to save on the scissors and cardboard.