You can create models in the workshop and publish them afterwards with the set number. If you need some parts you can create them (see here: https://mecabricks.com/en/forum/topic/630) or you hope that your part will made one day by the Admin (Scrubs). For new part requests use this page: https://mecabricks.com/en/forum/topic/50. Hope this helps.

thanks

it's not easy to create but I will still try
I do not have illustrator

Inkscape is free.

I managed to have illustrator
now, create the piece
not easy

Thanks 😃