I ended up doing some research and found a couple guys that used the semi-clear water line for appliances like an ice maker. I stole that idea. This stuff is cheap, $5-10 for a roll, Wich will do at least 15 cupholders. I used the 1/4" ID for cup holders and 3/8" ID for the speakers, the 3/8 wouldn't make the bend for the cupholders I found out later.
I'm not going to get in to the wiring too much. I used waterproof rgb strip LEDs, rgb wiring and connectors. I put connectors at each light location as well as between each piece so I could leave for instance the 3 cupholders and speaker hooked up and remove the interior piece they are mounted in.
It is absolutely necessary to heat each tube up to make the bend, and press each end on the rod about half way. Without heating it, the tubing tries to straighten out and splits to a point of failure, so I got to them all twice.
For the speakers, I didn't take any pics, but I used the larger hose, the 1/4" fits inside it almost perfectly, I added a bit of hot glue to each side to join the ends together. The mounting screws also run through the tube. There's not a good place to stick the LEDs like on the cupholders so the I sized the strips to a point where they basically held themselves against the tubing, then as it was tightened down, the vinyl behind them holds them tight, so far so good.
There is also one strip in the storage cubby by the motor, the led strip is pressed in to a piece of aluminum c channel for a very snug fit.