My 4 year old insisted that mommy and daddy's cups need lids like her and her sister's cups had. She said we HAD to print one for EVERY CUP.She insisted this for months. So I finally caved, and we went down stairs with a cup and designed a lid for it.She told me what she wanted, I took the measurements and keyed it into openscad. She clicked print & colored it because it had to be blue, and we had white plastic.