A=P6->F, B=F->M42 tube, C=M42-M42 helicoid, D=M42->E, & E=E->Z rings

The helicoid goes from 15 to 26mm at its maximum position in this pix,
this combination can focus from a little over INF to 0.5m as its MFD.
Of course you can use F->Z adapter(FTZ) instead of B,C,D,& E rings,
but you loose short MFD of 0.5m. Otherwise you can use A and F->EOS
and EOS->Z with builtin helicoid adapter in order to obtain short MFD.
(P6->EOS and EOS->Z with helicoid adapters together is much better.)

(shot by a7R2 + CV APO-LANTHAR 50mmF/2 Aspherical @f11)