Best way to scratch build a pressure hull for a 1/72 U Boat Type VII C-41

Thanks for any help I know Yankee models makes a resin one.

Can anyone help

I would either mold curved sections of flat styrene over an appropriate diameter plastic pipe by immersion in boiling water or cut the pieces out of plastic pipe . The styrene will be easier to glue as you are working with the same material as the kit .
The pipe will likely be PVC or ABS . Epoxy may be needed to fasten .

I believe Glenn Cauley had some tips on scratchbuilding one. Think he has a website.

Here is a link to the Glenn Cauley website. Looks like some great info!
https://gc-scalemodels.ca/U505/index.htm