An anonymous reader writes "OpenBeam USA is a Kickstarted company that builds open source aluminum construction systems (think high-quality erector sets). One of the main uses for the systems is building 3D printers, and creator Terence Tam is heavily involved in the 3D-printing community. He's now put up a blog post about some disturbing patents filed by MakerBot. In particular, he notes a patent for auto-leveling on a 3D printer. Not only is this an important upcoming technology for 3D printers, the restriction of which would be a huge blow to progress, it seems the patent was filed just a few short weeks after Steve Graber posted a video demonstrating such auto-leveling. There had also been a Kickstarter campaign for similar tech a few months earlier. Tam gives this warning: 'Considering the Stratasys — Afinia lawsuit, and the fact that Makerbot is now a subsidiary of Stratasys, it's not a stretch to imagine Makerbot coming after other open source 3D manufacturers that threaten their sales. After all, nobody acquires a patent warchest just to invite their competitors to sit around the campfire to sing Kumbaya. It is therefore vitally important that community developed improvements do not fall under Makerbot's (or any other company's) patent portfolio to be used at a later date to clobber the little guys.'"