I still need to properly finish or redo the Manta, as it's one of my earlier models and not very good. It's a very interesting design and has had a lot of attention.
No kit is available, but if I remember correctly Terry Harner in the USA has developed a combat RC model kit out of it, after winning several championships with his original built inspired by my 3D image. Other people who've built the Manta since for RC flying all agree that it flies exceptionally well, most likely due to the wing design.