Step models for PCB footprints

Hello

We are considering adding 3D step models to our PCB footprints.

Where does one find these 3D models in order to do this?

I found a place on the web that has 3D models for download but they have a different file extension than .stp.

I downloaded one and tried to map to an existing PCB footprint but the step molel packager didn't see the model extension .skp that it was created in.

I know of a 3rd party software program avaliable to help do this but not everyone will be able to afford to purchase it.

Any ideas on how to accomplish this?

Thanks,

Carvey