Shameless plug:<p>Bld3r.com co-founder here.<p>I started working on bld3r, because i was unsatisfied with thingiverse (owned by makerbot/stratasys). I'd like to see the community put a stop to a potential facebook-like hold on 3D model sharing learning since we are learning makerbot is very rapidly changing their culture from open hardware cultural icons, to an anti-social corporate subsidiary.<p>I'll hit some fairly basic bullet points:<p>* We are a functional 3D printing repo and social network, and in the top 3 alternatives to thingiverse.<p>* We on github (AGPL), and i'd happily accept pull requests: <a href="https://github.com/bld3r/bld3r" rel="nofollow">https://github.com/bld3r/bld3r</a><p>* We are built on google's app engine, so you can take our site and use it as a base for building your own social network and launching it in a couple hours or a couple of days.<p>* One major feature is that you do not have to upload 3d models to us. You can if you want, but you don't have to. We'd actually prefer if people host files elsewhere (via dropbox, github, tpb, etc., even thingiverse). You can then submit a link to your object and it'll appear on our front page crowd-sourced with reddit-style voting.<p>* We do not sell 3d printers, so if you do, we'd love to give you some free advertising while we grow our site. We are currently working on a contest feature, so within a month, if you want to host a contest, you can design what you want on our site, and launch it to promote your printers (Lulzbot was the first of such manufactures to do so, and we are very grateful to them for the notable bump in traffic and name recognition).<p>There are many more things we do to prevent even ourselves from exploiting a network effect in 3D repos.<p>We are not without our warts right now (this is neither of our main occupations, it's just a labor of love to keep 3D printing open), but please give the site a visit if you're interested. I live in SF and my co-founder lives NYC. We'd both be happy to get a beer and talk about the site if anyone is interested in using it as a base for another open social network.<p><a href="http://www.bld3r.com" rel="nofollow">http://www.bld3r.com</a>