Step 1: Getting Started (design)
What you'll need:
a short length of 1/2" copper pipe (~5" long)
a short length of 1/4" copper pipe (~5" long)
a length of plastic hose with 1/4" inside diameter
a drill and a 1/4" drill bit suitable for drilling in metal
a hacksaw or a tube cutter
a torch, flux paste and some plumbers solder
Optional but nice:
a drill press with a vice
a pipe flaring tool
If you intend to actually test or use it you need an air compressor with a blowing attachment.
Step 2: Putting It All Together
I bent the end of the 1/4" tube ever so slightly. I then put the the two together. The opening of the 1/4" tube should lean towards the front of the 1/2" tube and should not come up more then 1/3 of the way to center. I then mounted the assembly in my vice so that gravity would hold the smaller tube in place. I used my limited plumbing skill to solder the two together.
Don't worry if you can't solder. The idea is to have a strong air tight bond (not water tight). You could use tape, epoxy, solder, cheater solder paste and a match, etc. Just ensure that after you are done that the two parts don't move, but act as one.
Safety Notice: Drilling metal free hand is just stupid and you are looking to get hurt. Torches are hot and you can burn yourself if you are not careful. Always follow the safety instructions that come with your compressor, blower attachment and any other tool you are using.
Step 3: Testing
I then took a little cup and filled it with baking soda. I took the hose off and stuck the little tube into the cup. I opened the valve and it blew white powder out the end like puffs of smoke. I started to wonder if the velocity was going to produce any result.
It seemed too diffuse so I tried to add a nozzle. That ended up with air blowing down into the cup a moment after it blew out the front. I took the nozzle off. I shortened the main tube when I was doing it but it worked fine after. NOTE: baking soda doesn't etch glass.
I filled the cup with beach sand and that did it. The sand goes absolutely everywhere, like into my mouth and eyes and hair. I see why an enclosure is a good idea. It etched the glass (quite quickly) as you can see in the last photo. I suppose the sandblaster could be taped to the end of the blower for one handed use and the hose could go in a bucket of sand for bigger jobs.
I hope this give you some ideas for your own sandblasting attachment and good luck.
Safety Notice: Don't operate without facial protection and don't point this thing at anything you don't want to get bombarded by grit. An enclosure or a respirator may also be a really good idea if you are operating it for anything except a test.