We didn't want to carve it or shape it, and we needed it a specific size so we ended up using new sand castle molds. We wanted four towers and four walls so we used almost three big boxes of rice krispies and five bags of marshmallows. I made two batches at a time but I had more than one wall mold, if you have less molds you should make less at a time. I also made the treats really dry, I used seven and a half cups of rice krispies per batch instead of six. To press it into the molds I used a rubber spatula.
To decorate it we were going to pipe either frosting or piping gel onto it to outline the doors and different details, but we ended up loving it without the extra details. The spires are mini rainbow cupcakes with homemade flags. The starfish are sugar cookies with pink sugar baked onto them, and the seashells are chocolates that I made with a chocolate mold. I used regular, white and pink chocolate.
The funny thing is, no ate it, so now we have a whole sandcastle that we can eat ourselves YUM :)