Yes there was a patent roadblock. The very process of laying down layers of filament to build a model was patented until 2009. Before that people could get in trouble for duplicating those designs. But afterward people could openly collaborate. DIY 3D printers exploded once people were allowed to develop them. And I remember being in the 3D printer groups and seeing people unwilling to infringe on the belt 3D printer patent that makerbot had, for example. Hobbyists were aware of patents and weary of infringement. I built my first printer in 2011 too.

EDIT: Here is an interview with the creator of the first hobby 3D printer. In Europe, unlike the US, research projects are allowed to violate patents. He explicitly calls out the expiration of the patents as the thing that allowed them to expand beyond just research. https://www.3dsourced.com/interviews/reprap-dr-adrian-bowyer...

“We never had any problem with Stratasys complaining about what we were doing, there was only one thing that happened: we got a letter, very nice and very polite, very conciliatory, from one of their legal people saying they had a trademark on the term FDM and could we please not use it, so immediately I invented an equivalent term, which was FFF and we just edited everything on the site to that instead. That’s the only time they tried to interfere or anything else with the project. They never complained we were infringing upon their patent, which we weren’t of course [research projects in Europe can research a patented technology for the purpose of improving it without any kind of patent infringement], and we weren’t selling any machines.

“Once the patent expired in 2009, of course the project was free to do whatever it liked. Coincidentally, that was just a few months after we got the first printer working. It all came together fairly nicely in that regard.”