I am hoping someone here can help me. I have purchased a Bob the Builder panel. I would like to cut out the large panel and have smaller squares all the way around it turning the squares to be diamond shaped and then triangles in between. How do you know what size squares and triangles you will need to accomplish this? I hope I explained this right!

you draw it on graft paper and measure the shapes and add seam allowance.

measure the part you want to surround-
then divide that by what ever goes into it---such as an 18" x 30" ---6 would go into---3x5---add 1/2" seam allowance and you need 15 6 1/2" blocks....
graph paper really comes in handy figuring out this stuff!
if the panal is not easily divided you could add a narrow border to bring it to a divisible measurement

Thanks for the help! I was racking my brain and wasting fabric trying to make it work! You all are the best!