First of all, welcome to The LaserBoy Forum!
Yes. Many people here have made their own RGB (V) projectors, including myself.
As far as I know all of the really cheap pre-made projectors have an internal controller that reads from an SD memory card.
A lot of people actually use LaserBoy to make the specific kind of ILDA files needed to work on these systems.
You could also get one and modify it by adding a DB25 ILDA port to it. Then you could use a modified sound card (aka LaserBoy DAC) to control it (or any of the other ILDA complaint DACs).
You will find they are also TTL modulated lasers. That means they only go on or off. There is no control over intensity. So you only get 7 color combinations. That part would be a lot harder to upgrade.
James.