No one will, or atleast should, straight up tell you how to make one. Monstertonics spent time and money creating a product and its just wrong to detail the construction so some one can knock it off.
That being said it should not be all that complex using readily availible RF transmitter and receivers. A few voltage and switching issues to work out, but pretty easy. The idea of controlling it in a spot will be more difficult. Because of the line of site, RF is the way to go. In a closed in "maze type" attraction, the signals will overlap and cause inconsistancies. If you are doing a trail type attraction, it should probably work.
I suppose if the light had a normally on function and effects were occassionally triggered, then you may be able to space them out enough to work.
I investigated this myself for a design , but shelved the project when control in close quarters got difficult.
Yeah, the're pricey, but a cool product. Have fun.