Need help with how to go about designing a mold for a quadcopter canopy

I’m pretty new to sketch up but have designed a quadcopter frame I will send to get milled out of 3mm carbon fiber. I need to design a couple pretty simple top and bottom canopy molds that I can send to my friend who owns a machine shop so that he can mill them from aluminum so that I can vacuum form canopys out of lexan. Im not sure how to go about designing rounded 3d shapes in sketch up. the bodys will be pretty simple and will basically be shaped like 2 twinkies… what is the best way to approach making these?

Your first step would be to post an image of what you want so that those of us who have no idea what a twinkie is, beside it being some sort of inedible chemical compound made into a delicacy for the american market, have a better idea of the shape you are after.

I am being a touch frivolous, but the reality is how do you want the twinkie shapes to interact. Two of them parallel like helicopter floats or intersecting at 90 deg to form a cross.
Are they rounded at the ends and have flat bottoms or simple cylinders cut off flat.
So many options when working in 3d.

The canopies will be top and bottom bottom pieces. the will attach to frame via magnets.

the concept will be simular to the TBS gemeni hexacopter but my quad will only have 4 motors so the shapes will be slightly different