General question here. In building a medium-format camera on one's own, the most obvious answer to frame spacing is "use a red window". If a person would rather have a reliable wind-on lever/knob for spacing, where to start? Scavenging the mechanism from a defunct camera is one option. Are there any achievable-without-a-major-industrial-process ways of building one yourself? I can think of a few different ways to implement the decrease in amount of wind-on needed from the start of the roll to the end but none that are that great. I'm apparently not the only one, since so many early cameras have problems with this.