I used to get slightly irritated when I'd see great projects that involved using a Silhouette when I didn't have one, so if I'm doing that to you now, I'm sorry! It is possible to do this without a machine; it's just a little more time consuming and the quality of the end result will depend on your cutting skills. I'm impatient. And sloppy. Which explains why I'm loving the Silhouette!
For my design, I used Honey Badger font and downloaded this simple bone graphic from the Silhouette store. I've had the treat jar for years (it was a flour canister in its past life before Smokey joined the family), but I'm pretty sure it's this $3.99 Burken jar from Ikea.
If you have a Silhouette...
Create your design using the Studio software, then print it out on stencil vinyl. Use transfer tape to apply the design to your glass, and smooth with a credit card or the scraper tool to ensure it's on there nice & smooth. Remove the transfer tape. Liberally apply etching cream over the design and let sit for 30-60 seconds. Scrape off the extra cream, and stick it back in the jar since you can reuse it. Wash off the glass, then remove the stencil.
Without a Silhouette...
So, warning, I haven't tried this, but I think it would work. If you have tips, I'd be happy to update this!
Create your design using software of choice (Microsoft Word would work just fine, or draw it if you are more artistically inclined!). Print the design, then trace it onto contact paper. Use scissors or a utility knife to cut out the design on the contact paper, and apply the contact paper stencil to your glass, smoothing it with a credit card or scraper tool . Liberally apply etching cream over the design and let sit for 30-60 seconds. Scrape off the extra cream, and stick it back in the jar since you can reuse it. Wash off the glass, then remove the stencil.
"Seriously, can I please have a treat now?"