We did our version of the sharpie mug project last week and it went pretty well. I bought some white mugs from Goodwill and had the kids plan our their drawings first. Then I let them draw on the mugs in permanent marker.
There are lots of variations of this project floating around. Here's what worked for us.
1. Cheap mugs. They are from the thrift store, but originally the mugs are from Ikea, Pottery Barn and Crate and Barrel. Basically the glaze has to melt in the oven and then dry again with the ink now on it.
2. Clean the mugs well. Ours had a few spots where the adhesive from the price stickers was still there and that part is an ugly brown after going through the oven.
3. Put the mugs in the cold oven. Then set to 425. Bake for 30 minutes and let cool in the oven.
4. Go read some books.
5. Remove when they are all the way cool.
I put ours in the dishwasher right after they cooled down just to see what would happen and all of the designs stayed put.
The kids thought this project was a blast and they love drinking out of their mugs now.