As bumpers are a likely requirement for 2018, now is a good time to check out local stores as they are often on clearance at this time of year and are more readily available than in January.
For reference for rookie teams, here is Frank’s Blog post from last year:
At champs, after two bumper-pounding regionals, our bumpers were a little thinner than at bag ‘n’ tag. And our 2-3/8 noodles we bought from Target were under a lot of scrutiny. We had to remove fabric to show that it was wear and tear that made our bumpers as thin as they were. Even then, having bought noodles that were not listed as 2-1/2" we were in danger of not passing.
While this was an immense frustration to the team, the inspector was 100% within rights to challenge our bumpers. Luckily, the lead inspector let us through. At bag, our robot was at the limit of robot volume.
I’ve never asked for a receipt, though I can understand why they’d be requested.
It goes like this: If an inspector is looking at something, and they think it looks not-legal, then they are expected to ask the team if they have documentation, or can otherwise demonstrate legality. For example, I’ve been known to ask a team for documentation on an electric solenoid actuator–just to make sure that it met the specs for that year. When they showed that it did (by pulling up the spec sheet on a phone), I signed off.