They are not that difficult to build. My husband built 2 PE-2's. The hardest thing was finding the prop. Most hobby stores don't stock the R designated propellor so you have to special order them usually. I have to say that these things coupled with seaswirls provide some of the best random current generation I have seen for medium/large tanks. Mustangs design is much more compact which is even better
We are using a black prop at the moment...not sure if it makes much of a difference when compared to the Octura 1250R...we did have to remove the metal nut though. We also put a guard of black eggrate (now that was hard to find) over the outlet as the reeftecs are on a wavemaster and I didn't want starfish/fish puree...