I love doing resin and epoxy crafts and am always looking for nice new molds. These Heart Shaped Diamond Edge Epoxy Resin Molds by ZeMooon fit the bill perfectly. They're a nice size for most coffee mugs, or glass cups. I love that you get a set of 4 so that you can make all 4 as a gift at once. I figured my grandchildren when they come over can make some nice new coasters for their families and I love how each one will be unique. They can choose their own colors w/ mica powders or alcohol inks and we'll do this outdoors. Just be sure that all the kids are supervised and have gloves on as well as N95 masks or a respirator on so that they don't breathe in any harmful smells. Doing it outdoors does reduce this. I've got tons of molds but the kids' favorites has always been the coasters because they're simple, easy to do and fun. We can knock this out in under 30 minutes (aside from it drying) and the kids can take it home the next time they come to visit. Plus on top of it being fun it's also useful. These molds are of very high quality and made to last. If you want to be sure they last even longer just make sure before they color anything or paint anything you spray them well with a silicone mold release so that once dry they come out of the mold without pulling it apart. Makes these molds last tons longer. To get a set of 4 molds for $15.99 is very reasonable.