I have no problem answering your questions! The Grob and the Jodel are both from plans drawn by a friend! His name is Hilmar and he also sells the plans! You can get them from the publisher VTH.de
There you can also get the material for the planes!
Art.-Nr. 6211140 (for the Jodel+material) Art.-Nr.: 3201383 (for the Grob) and Art.-Nr.: 6211206 (for the canopy and material for the build)
The other method is to build a depron splitting device which is also described by Hilmar and the German magazin FMT!
Sorry, all in German!