Easter Egg mold

Hello everyone,

I'm trying to do a mold for my chocolate easter eggs but I'm having some difficulties with the details.

I want to add some lines in the mold so the final chocolate egg can have some details on it.

I tries a lot a different tools but I can't fill the mold with a pattern. I tried the wrap one for exemple, but i can't get rid of the "open sketch" message. I tried to "convert" it but the problem still the same.

If you have any ideas of which tools I can try and how, I will be grateful