This is a low poly model of a greek balista, Oxybeles, of the 200BC period. The model is animated and has a simple rig made out of helpers and uses PBR materials..

The frame has an optional part, the exterior metal plating.
The upper part of the model can be further animated via the top bone, for aiming(rotational) animations.

Also two wood versions of the ballista's maps are available.

Sketchfab preview id:
https://skfb.ly/69xHV

Polygons: 2,333
Vertices: 3,213
Animation:
0-5 idle
6-264 crank
265-269 attack idle
270-322 commence

The scene was rendered using Mental Ray, w/ diffuse, normal and specular maps.

The scene contains:
-animation of the oxybeles
-two wood versions
-2048*2048 PBR maps(diffuse, normal, metallic, roughness, height and AO)