I’m not one for hypothetical situations, but this situation may become real next year for us.
What if you designed in CAD a robot base in the fall, built it, and then liked it so much, you decided to use the base in the next season. If you used the exact base you made in the fall for your PRACTICE BOT, would it be considered legal if you remade the comp. bot during the build season.
Practice bots are not regulated by FIRST. Your practice bot could have a flamethrower and a jamming device on it, and they wouldn’t care in the slightest.
You just can’t compete at a competition with it. 
The rules, as I’ve always understood them, are that parts on your COMPETITION robot cannot be fabricated prior to kick off. Your practice bot can be whatever the heck you want it to be. So, by my understanding, if you replicate parts from your practice bot (or your entire practice bot, should you wish) for your competition robot, it’s totally okay.
The parts could be released as COTS items. You should put your cad files and related materials on your website, here on CD and on the FIRST forums. A lot of teams do this with their code base each year, so they can reuse portions. The thing to remember is that these parts are now to follow COTS rules.
You could also sell the parts on your team website, if you go the prefab way… This would calm the fire if controversy arises.
(take a look at 221 Robotic Systems and the robonauts…)
Alec,
I see robot inspector in your future.
it would be like using the same base in your cad as the previous years robot-which from my understanding is legal
Combine this with a water game and we have winner…
Possible 2018 game? How about in 2019? Or 1991?
No it would not be legal if you are producing parts from a design done before the build season unless you release the entire CAD files for it. Selling parts is also not away around it unless you are willing and able to produce those parts in a reasonable amount of time for any/all teams that wish to purchase them.
As Alec said, the practice robot itself is not governed by any rules. The competition robot is, and if you used your offseason drivebase as your practice bot and want an identical competition robot, that could be illegal per rule [R18]*
The details are in the blue box, but essentially, if your preseason designs were used exactly with no modifications on your competition robot, it is illegal.
There’s nothing that says you can’t use it as a practice robot, but if you want an identical practice and competition robot, that would require that your competition robot also use the exact same drivebase, which would likely be in violation of the rules.
*for this year’s rules. Future rules may be different.