Marking your carboy
 

This shows how I etched gallon/half gallon marks on my carboy using glass acid etch.
This is what you need:
1. Carboy
2. Masking tape 1/2" and 1" (or whatever you want, I already had these)
3. Armor Etch Glass etching (got it from Roberts Craft)
4. Flux brush
5. Scrapbooking letter set.
http://www.motopartsearch.com/bike/carb1.jpg
Add a half gallon of water at a time, and mark it with the masking tape. I just centered the 1/2" tape over the water line. Then add your numbers from the stencil set. Then dump out the water.
http://www.motopartsearch.com/bike/carb2.jpg
Add the etching cream with the flux brush and let sit for about 10 minutes.
http://www.motopartsearch.com/bike/carb3.jpg
Wash off the acid with tap water and remove the masking tape.
http://www.motopartsearch.com/bike/carb4.jpg
And that's it
I got a little bleed through with the acid, but my masking tape is pretty old.

Whoa! Killer...and is that really a 7 gallon carboy?

It's a 6.5 carboy but you can get 7 in it.

Beauty...i have a 6.5 and two 5 gallons. Thanks for the post...I'm going to do this to both of them!

That looks great man. Is that glass etching cream something you can pick up at a craft store, or do you have to get it somewhere special?

Got it from the craft store. Any of them should have it. It's a pretty common item.

Or you can just be lazy like me and use 3M waterproof medical tape. It doesn't mind being washed, and is really easy to mark with a sharpie.

that's awesome. thanks for sharing

Hmm....I am definately going to have to try this..

I like it! thanks!