Low-poly modular robot parts for a fast-paced sci-fi game

I need individual robot parts, not a full character. These are modular components used to assemble combat robots in a fast-paced sci-fi game. The style should be stylised futuristic, readable from a top-down camera, and clearly communicate function (engine, weapon, thruster, etc.) without unnecessary detail.

Parts overview
The initial set includes:
Several jet engine variants (directional thrust, rotating, two side)
Standard engine (with visible exhaust outlet for smoke/VFX)
Cannon / weapon module (designed as a standalone block)
Each part is an independent asset

Scale & dimensions
Each part fits inside a 1×1 unit footprint
Approximate height: ~0.6 units
Pivot at the bottom center, aligned to grid

Geometry
Low-poly, game-ready topology
Clean shading, no flipped normals
Each part may consist of one or multiple meshes
Triangle count kept reasonable for Synthy Polygon assets-like game

Collision
Each part has a simple box collision (1×1 unit)
(visual mesh does not need to match collision exactly)

Materials & rendering
No textures required
Minimum 2 materials per part:
Base material – player-colored metallic surface
Bright/emissive material – used for lights, energy cores, indicators
Materials must be cleanly separated (no vertex color dependency)
Emissive areas should be clearly readable and minimal

Animation & rigging
No rigging
No animations
Parts are static modules; all movement and effects are handled in-engine

File delivery
FBX (required)
Clean naming for meshes and materials

Acceptance criteria
Imports correctly into Unity
Correct scale and orientation
Pivot at feet / base
Assets snap cleanly to a grid when assembled

Notes
If you need clarification on:
Visual language of engines vs weapons
Emissive intensity / placement
Color palette assumptions for player materials
ask before starting high-detail work so we can lock the direction early and avoid revisions.