About this 3D model

my parts have tree slits instead of two. joint lenght is constant. For internal animatronic bowden system. Feel free to help me making this a customizable piece, because i cant do openscad. I added a plate but i think its best not to print them all at once. should be scalable a bit.. but not tested yet. Print plate twice and assemble in double lenght... put some elastic sock over finished piece and multicoat that with silicone.. or maybe this could be used: http://www.insulationproducts.com/images/IP49VP%20-%20Very%20Flexible%20Heat%20Shrink%20Polyolefin.pdf