Thingiverse is primarily for printing. Because printers need support structures, many "parametric" designs are partitioned by default. Look for models labeled or "Snap-fit." 6. CGTrader (Free Section) License: Royalty Free.
You cannot separate the wheels from the car. You cannot cut a hole in the wall. You cannot isolate the handle from the mug. partition 3d model free download
P.S. Always check the license. "Free download" does not always mean "free to sell." Respect the artists. Thingiverse is primarily for printing