Structure

Deciding what materials to use where can make or (literally) break your season.

Building a reliable robot starts with a solid structural foundation, the frame and supporting components that everything else attaches to. A well‑designed frame provides rigidity, aligns mechanisms properly, protects internal systems, and ensures your robot meets FRC perimeter and bumper rules.

In FRC, you’re constantly balancing:

• Weight (lighter = faster, easier on motors)

• Strength (won’t bend or break)

• Stiffness (won’t flex)

• Manufacturability (can your team actually make it?)

• Cost & availability

No single material is best everywhere.

Material Choices

Material	Strength	Weight	Impact Resistance	Stiffness	Best Use
Aluminum	High	Medium	Medium	Medium	Structure
Polycarb	Medium	Light	High	Low	Intakes, guards
Perf Poly	Low	Very light	Medium	Very low	Electronics mounting
Steel	Very high	Heavy	Medium	High	Shafts, high-load parts
3D Print	Low–Medium	Variable	Low–Medium	Low	Custom parts

1. Aluminum

The primary structural material in FRC robots.

Key properties: Excellent strength-to-weight ratio, easy to machine and cut, available in many forms (tube, extrusion stock, plate). Most FRC robots are built primarily from aluminum, with alloys like 6061, 5052, and 7075 commonly used.

Common Uses: Drivetrain frame, structural members, gussets, spacers, shafts, gears, and plate.

Limitations: Can bend under high impact, less stiff than steel

Default to aluminum when: You need structure, you care about weight, or you can machine parts.

The 2025 kitbot used aluminum tube structure and machined aluminum gusset plates.

2. Polycarbonate

Polycarbonate (often called Lexan) is the most common plastic in FRC.

Key properties: Very high impact resistance, flexible (bends instead of breaking), lightweight. Polycarbonate is widely used in FRC because it can take hits and return to shape without cracking.

Common uses: Sheets, rollers, intake arms, mechanisms outside the frame, shields and guards, and other flexible structural elements.

Limitations: Low stiffness (can flex too much), can deform under sustained load

Default to polycarbonate when: A part will get hit and needs to flex instead of fail

The 2026 kitbot used polycarbonate sidewalls for the hopper

2b. Perforated Polycarbonate

Polycarbonate sheet with a grid of pre-drilled holes.

Key properties: Lightweight, very easy to assemble with, modular mounting pattern. Use perf poly when you need fast assembly and a flexible layout for components.

Common uses: Sheets, electronics boards, and quick prototyping.

Limitations: Low stiffness due to holes, not suitable for structure

Default to perf poly when: You're prototyping, need a lot of hole in one piece, or wiring your electronics.

3. Steel

High-strength metal used selectively.

Key properties: Very high strength, high stiffness, good wear resistance. Steel is stronger than aluminum but significantly heavier and harder to machine.

Common uses: Corner brackets, shafts, gears, high-stress components, adding weight to shift your center of gravity or adding to inertial momentum.

Limitations: Heavy, harder to fabricate

Default to steel when: Loads are very high, failure would be critical, or more weight is needed in certain positions.

4. 3D Printed Materials

Additive manufacturing plastics - typically PLA, PETG, ABS, and Nylon.

Key properties: Highly customizable geometry, fast iteration and prototyping, lightweight. 3D printing is widely used in FRC because it enables rapid iteration and custom parts that would be difficult to machine.

Common uses: Sensor mounts, wire management, pulleys and spacers, prototypes

Limitations: Weaker than metals, layer-based weakness (direction-dependent strength), can fail under shock loads

Default to 3D printing for: Custom geometry, low-to-medium load parts, rapid iteration