Yes that's the answer i needed, thank you so much! I will give this a try laterAh I think I might have read your question wrong. You are using Item Shapes
In that case yes, I think you need to match the item aspect ratio with the shape size.
so a 1x1 item should be 51x51 and the 2x3 item should be 2*51x3*51 (51 is the pixel you want your base unit the be. It is up to you to decide what that is, it depends how big you want it to be on screen compared to your max resolution)