Glad to see I wasn't the only person who had this idea! Even better, someone beat me to it in execution. I was wondering if there is a notable cost-saving in printing vs purchasing? Did you have access to a fab-lab with a 3d printer or did you have them fabbed and shipped to you?
If you happen to have a printer already it will run you probably about $1 in material. These kinds of things make most sense when there is a critical mass of useful things to print so much that it makes sense for a farmer to buy a 3D printer. At the moment there is not terribly a whole lot on thingiverse tagged for farmers. I'm hoping this continues to evolve swiftly!
Things tagged for farming on thingiverse -> http://www.thingiverse.com/tag:farming
It costs $3-4 a wheel on our printer. That is just for materials, not the cost of the printer or electricity to run it. The purpose of making these wheels was to get custom specs on the wheels to alter seed size, seed spacing. I imagine they can be printed at local makerspaces or commercial 3d print shops. I do not plan to duplicate any of the authentic Jang seeder wheels. I just want to create and share my customizations.
I posted a new design tonight for the YX80. Gives you 80 seeds per rotation of the wheel. YX is sized for arugula seeds. Increased hole size from 2.5mm to 2.6 mm.