Prototyping

The cost of finding a problem during prototyping is a few hours and some scrap wood. The cost of finding it after you've lasercut aluminum plates is a week of rework. Prototyping exists to answer one question before you commit to a full design: does this actually work?

A common mistake is jumping straight into CAD after the brainstorm. CAD looks finished and precise, which gives a false sense of confidence. However, a beautiful CAD model of a mechanism that doesn't work is still a mechanism that doesn't work. You want to answer the fundamental questions with cheap, fast experiments rather than fabricated parts.

Materials

Use whatever is fast and cheap. The prototype does not need to look good.

Material	Good for	Notes
Wood (plywood, 2x4s)	Structural frames, mechanism geometry, range of motion	Easy to cut and drill. Heavy, but that doesn't matter for prototyping.
Cardboard	Quick mockups, sizing, spatial planning	Good for figuring out whether things fit before committing to real materials
3D prints (PLA)	Complex geometry, pulleys, brackets, spacers	Fast to iterate. Print at moderate infill and don't worry about strength.
Pool noodles / foam	Simulating game pieces, bumper mockups	Buy a few from the dollar store at the start of every season
Old robot parts	Anything in your inventory	Spare gearboxes, motors, wheels, structure. Don't be precious about reusing them.
Zip ties and Tape	Holding everything together	Temporary by nature, and that's the point

The best prototype is the one that gives you an answer fastest. If you can test a concept in 20 minutes with cardboard and zip ties, do that before spending 3 hours printing something.

What to test

Not every prototype needs to test everything. Be clear about what question you're answering, and design the test around that specific question.

Question type	Examples	How to test
Geometry	Does the game piece fit? Can the mechanism reach? What angles work?	Build a static mockup and physically check
Force / speed	Can this intake pull in the game piece? Does the shooter have enough energy?	Build a powered prototype with a real motor
Integration	Does this mechanism conflict with the drivetrain? Is there room for both the elevator and intake?	Mock up the full robot footprint with cardboard or foam and check clearances
Consistency	Does this work once, or does it work 50 times in a row?	Run the prototype repeatedly. FRC is about reliability.

How to run a test

A prototype test that's slightly structured produces results you can actually use to make decisions. Without structure, you end up with "yeah it kinda worked I think" which doesn't help anyone.

1

State what you're testing

Write it down. For example: "We're testing whether a 4-inch compliant wheel intake can pick up this year's game piece from the ground at a 45 degree angle."

2

Define success

What does "working" actually mean for this test? A success rate? A speed? A distance? For example: "Successfully intakes the game piece 9 out of 10 attempts from varying approach angles."

3

Run multiple trials

One successful attempt does not mean it works. Run at least 10 to 20 trials if the test is fast enough. Record what happens on each one, whether that's video, notes, or just tally marks.

4

Decide what to do next

Based on the results, you have three options: iterate on the current concept if it's close, try a completely different approach if it's not working, or move forward to CAD if it's validated.

If a prototype isn't working after a few iterations, the problem might be the concept itself rather than the execution. Getting attached to an idea that doesn't work is one of the most common and most costly mistakes in build season. Know when to kill a concept and try something different.

When prototyping happens

Prototyping should happen mostly in weeks 1 and 2 of build season, overlapping with strategy and concept development. The goal is to have your main mechanisms validated by the end of week 2 so that detailed CAD can proceed with confidence.

However, prototyping doesn't fully stop after week 2. If you're making significant design changes mid-season or between events, prototype the change before you build it. The same principle always applies: test it cheap before you commit.