I am for these primitives.
I've found this part Duplo arch u977 has an underside center divider (missing in the part model), and these primitives will fit nicely.
https://www.ldraw.org/cgi-bin/ptdetail.c...s/u977.dat
I've found this part Duplo arch u977 has an underside center divider (missing in the part model), and these primitives will fit nicely.
https://www.ldraw.org/cgi-bin/ptdetail.c...s/u977.dat