I found a book of fancy repro etchings, for $6 or something (ages ago) just for this sort of purpose. But you can use anything... photos, book covers, musical scores, art books, kids drawings...
This set of yarn bowls is different than the last one I made, or the last couple. No lid for starters. The lid is annoying on the last one. I never ever use it as intended (for yarn to come through). Ever.
For a tutorial to make these in any shape or form, go HERE and for lots of other crocheted card thingy's I have made and drawn patterns for, go HERE.
If you print out the diagram at A4 it should be right. I don't think a bit different will matter much. Then, slice 3-4mm off the sides and lower edge of the side and off each side of the hexagon. This makes the medium sized bowl. Repeat for the smaller one. I decided the big bowl’s sides we’re quite high so took 10mm off the rim for the medium and a further 4-5mm for the smaller.
Go to the next link for more pictures of the three sizes in a subsequent post: