No, not at all.
First I lightly dusted the molds. and dusted each use. I used corn starch. After pressing in the rolled out fondant, let sit for a few mins, tap out, then lightly rest them back in the mold so they can set while keeping the shape. After several hours, I took them out and let them finish setting. Depending on the humidity, you may want to let them rest in the molds a little longer. Once firm, dust or paint, or both.
If you decide to do both, paint first. On some, I alternated painting stripes then dusting stripes and lightly dusted super pearl. On the white ones, I just dusted super pearl.
I bought 8 colors including copper, moss, sand, and a variety of natural tones that would blend together well. I found and bought a variety of shells to use as models. The thin black lines were with food markers. I made over 100 in different shapes and sizes and used candy and soap molds.
I think they worked out well.