I needed a model of a Rpi3 for a project and alexandre_willame was kind enough to have put one up. It's a really great STEP and very accurate, but had too much shit on it. So, I deleted everything not relevant to making a case for it and this is that STEP file.
The only things it has are the board, SOC, overhanging connectors and the GPIO pins. It's mainly centered around being easy on the software as Fusion has recently taken a turn for the worse.
Update: Made a second version. It's ugly AF but it has even less bodies to import due to a combine operation.