Hi
Since you want to create an object that maintains two ends with variable distance between then split into four as you have drawn, the half cylinder ends as per attachment, the trick is to build cutting holes top, bottom and side, hide any lines not needed to be seen (outline of hole), add outlines or faces (e1,e2 you can delete these for your project) as required. See my models on warehouse...cylinder, pcmoor
the rectangle sides should be no problem, hide the lines at the joins. The position of components can be tricky, but i let you give it ago, let us know if you need further help
Cheers
Philip
half cylinder.skp