Thanks for your many replys!
I try to answer for everyone...
Vossie: Yes it helps, i got some nasty flares without my hood and now they are gone. I did´t calculate lenght, but it has no vignetting. I can put my fingers inside about 1,5cm and it has no effect. And eaven it woud vignett it´s easy to remove vith LR.
timmy_650: I had almost everythig that i needed at home so it did´t cost much at all.
It took some time to do though. I spended about 5 hours with it if i don´t count waiting time to epox and lacquer to dry.
CarlTN: I used SP230 epox that threads in room temperature.
mackguyver: It is unbelievable easy to build some CF -parts, but i don´t have now time to explain more.
BL: I don´t have any filters attached to my 40mm lens.
surapon: Thank you very much!
sama: Thank you to share my small vid that i just made for fun with my 6D. I can say that it was a hard work to keep camera still, because my younger (1 year old) son was hanging on to my trousers all the time
Using that cf vinyl sheet would be so cheating!