This is the most dangerous project I have ever done with a group of students. They didn't look like they believed me when I told them that, but there were three very dangerous steps.
#1: Sharp Glass. The students removed glass with sharp edges from old wooden frames of questionable origin. The glass was then carried back and forth across the classroom over several days. After removing the glass from the frame, the glass was cleaned and then covered in clear contact paper. The students then put the glass on top of their reference image, and traced the image with permanent marker onto the contact paper.
#2: X-acto Knives. The contact paper covering each part of the image to be etched had to be removed for the etching cream to work. Students carefully traced the marker lines with x-acto knives and peeled the sections of contact paper away from the glass.
#3: Dangerous Chemicals. Once the design was fully carved out of the contact paper, it was time for the etching cream. We used Armour Etch, which is easy to use, but as their website states, "not intended for use by children." Only two students at a time used the chemical, under close supervision, and never touched it without immediately washing their hands (this was probably overkill; I have used this chemical for years, even touching it extensively, and experienced minimal consequences). The etching cream was left on the glass for at least half an hour, and then scrubbed off using an old toothbrush.
During the rinsing process, the contact paper also got peeled away, and the freshly etched glass was left to dry in the dish rack in the classroom.