Center rectangle on x-y plane

done by offsetting each layer

sketch fillet R7.00

a circle

set guiderails using intersect

filleted the bottom

extruded circle at the top

fillet R12.00

connect them using lines and fit point spline and mirror over

Lofting gave me something liike this, and even creating a guide rail didn't help because errors popped up. I figured out that the best way to do it is section by section, starting with the cap and every section where I had a rectangle within a rectangle had to be broken apart.

I wanted to add the ridges

300mm x 104mm x 50 mm rectangular prism

taper 7 degrees

filleted with 2mm inside thickness

create a midplane

drew a rectangle and moved it

filleted  4mm

extrude -30 mm

rectangular pattern tool 7 x 2 

filleted 10 mm

filleted edges

rectangular pattern

-extrude 21.5

shelled 1.5 mm

extrude  30 mm

filetted edges

extruded

Extruded fit point spline symmetrically 8.89 mm

extruded

extruded as new body

shelled

filleted