Does anybody know if it’s legal to have a compartment that can open and close to drop pieces as the match goes on to cover more tiles?
no, they must be attached to the robot
For any question about the legality of something, we must turn to the game manual (or the Official Q&A). As you read the game manual (https://link.vex.com/docs/2022-2023/vrc-spin-up/GameManual ), keep in mind that the game manual tells you things that you must do, and things that you are prohibited from doing. It can’t tell you everything you might do, so if the game manual does not prohibit an action, then it is generally legal. The game manual does not generally discuss any particular game strategy or mechanisms you might use.
In regards to your question, take a look at SG4 regarding expansion and G5 regarding detachment of pieces in the game manual.
The parts must be connected to the robot and only be dropped during the 15-second endgame period.
Completely depends on what you mean. If you mean a container with nuts and screws that sporadically drops these out during the match, no. Also, whatever you end up using needs to be attached to your robot, so dropping screws at any point would probably just get you a dq. if you mean a container with lumps of metal on a string that you could release in the last 10, then probably yes. Also, you could check the game manual, which has the answers to many of life’s most pressing questions. I have read it a couple of times, and it really does help.
You will not pass inspections if you have parts that intentionally disattach from your robot. If they unintentionally come off of your robot, they will not counts as covering tiles. Hypothetically if this was allowed, it wouldn’t be useful as you would be expanding outside of the expansion limit before the expansion time. I highly recommend that you read the game manual as this has all of this information in it.
General rule of thumb: if the game manual doesn’t prohibit it, it’s legal.
Note: make sure it’s still connected to your robot, and consider that expansion can only occur in the last 10 seconds.