That's free as in libre, not gratis. I've just about finished building my f-stop timer. Without blowing my trumpet too hard, it has most of the features of the commercially-available units and is easier (especially for beginners) to use. It's based on an Arduino, which is a very accessible platform. If you can follow a schematic and solder, you could build this; if you can program in C++, you can improve on it. No programming skills are required though, that part is all complete. Do people have a serious interest (not just dreaming) in building this from GPL schematics and source code? Total cost for a unit would be in the ballpark of $40-60 plus a few hours of your time for assembly (basic electronics & mechanical aptitude is required). If there is sufficient interest backed with prepayment, I could have a small run of PCBs made up to simplify construction greatly and that would raise the cost by maybe $10-20/unit. Features are: - 0.01 stop resolution - drydown correction with 0.01 stop resolution - timing to approx 1ms resolution - max exposure 1000s, min exposure 10ms (limited by enlarger warmup) - direct numeric entry of EV in decimal stops with 4x4 keypad - can save/load 7 print-programs to/from flash - up to 8 exposures per program - each exposure has a 14-char textual description to prompt you - exposure footswitch and focus mode - menu-driven operation with text prompts - audible success/fail notifications - transfer saved programs to/from PC (future feature) - 16x2 red-backlit LCD with layer of rubylith to make it safe - adjustable LCD backlight brightness Major things it lacks at the moment: - support for more dodges than the base exposure (e.g. three separate 1-stop dodges), i.e. concurrent dodges / operator-is-an-octopus mode - closed-loop mode and enlarger warmup correction - split-grade automation (input a contrast change, have it calculate new times) They're not things I need at the moment, so are lower priority. I'm online for only another week and then off for five weeks so I'll post photos etc of the timer after I get back in October. Let me know your thoughts.