This was so much fun! I was completely addicted to it for a couple of weeks around Christmas, but I couldn't say anything because I didn't want to spoil the surprise.
The hardest part of the whole project was....finding etching cream! I ended up having to order it online from walmart.com.
I'll try to write up a tutorial later, but here are a few little tips...
Art Philosophy Cricut Cartridge (ok, you can use something else, but why?)
Vinyl or Contact Paper
Pyrex Glass Dish (I bought these at walmart too)
Pick images that are fairly simple with large open areas.
It's easier to work with a flat surface for your first piece.
You have to place each letter separately when working on a curved surface.
I used a wide popsicle stick to spread the cream. You can also scrape the excess off and put it back in the jar.
Do not spread the cream too thick...it will drip!!
Do no get it on your hands!! It's acid! Be careful!!!
Sorry my pictures are so bad. It was really hard to photograph these.
This picture might spoil a surprise, but it shows how I placed the vinyl letters on the plate. You might want to add some masking tape or more vinyl to the glass areas around the letters to give you more room when spreading the etching cream so that you don't accidentally etch the open areas.