I think I would try beading the design on before cutting it out. I could still cut the individual curved designs between each section of the shell as shown and stitch them on then continue beading.
LujzaMarko / P ako Paulína wonderful artist from my home country - Slovakia!
Should you enjoy arts and crafts you will appreciate this cool website!
gentlewomen - I like that this is called 'Gentlework' - it does look gentle :)