Ian Fritz's Triangle VCO

I built Ian Fritz's Teezer VCO recently and it is extremely clever. It is probably the most unique design that I have seen for an Synth widget for a long time. I can see why he got grumpy when Mr. Blue Lantern allegedly ripped of his design. Anyway it piqued my interest in some of his other VCO designs on his website -- I know that I have looked at this one before, as it is dated 15 years ago, but for some reason I never really took it in. So I have done a layout that is P'n'P compliant and will give it a go.