I was absent for a long time - so much work!
But I'm back. Thank You so much for suggestions. Most of this will be realized.
Currently I'm working on Fokker cowl nuts:
Almost ready - casting block prepared. But... its so small - diameter (in the thicker part) is 0.3mm. OK, it's for Bertl - he'll ménage


I've started also Bentley BR2:
Cylinder base - exactly the same number of ribs as in the case of original:

crankcase:

spent about 10 days for a preparing crankcase - extremely difficult to keep geometry. Few unsuccessful attempts:

Thanks a lot, Lukasz