Where to download 3D print files from

Paid for 3D Print Models

Blend Swap – https://www.blendswap.com/

DO3D – https://www.do3d.com/
(Great for full body suits, armour and helmets)

Galactic Armoury – https://galacticarmory.net/

Gambody – https://www.gambody.com

Hartolia Miniatures – https://hartolia-miniatures.fr/en/

Loot Studio (Miniatures) – https://www.loot-studios.com/

MyMiniFactory – https://www.myminifactory.com/

Free 3D Print Models

3DMag.org – http://3dmag.org/en/market/

3DPrintKings – https://3dpkings.com/

GrabCad – https://grabcad.com/

Pinshape – https://pinshape.com/

Printables – https://www.printables.com/

Thingverse – https://www.thingiverse.com 

YouMagine – https://www.youmagine.com

3D Artists and Modellers

FotisMint – https://fotismint.com/

Geoffro / Hex3D – https://www.patreon.com/Geoffro

SidNaique – https://www.sidnaique.com/

Engineering Products and Components

www.mcmaster.com – https://www.mcmaster.com/

(Not a 3D Model site per se, but has 3D objects for many of their products)