Regarding the canopy ....
If you can not produce a good one, you can ask my friend Chris from Germany, he created molds from the canopies of my models I gave him.
Regarding the calculations of interior and exterior.....
I do not do calculations but makes attempts, because I do not have software to create layouts for models.
Also, sometimes I use my two friends to create layout parts for my models because they have suitable software.
YOAV