Just keep in mind that I’m pretty sure polymer clay has PVC in it, so you should minimize if not eliminate its use in a laser.
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Easier though would be to run a strip of double sided adhesive on the back of the cabochon. (I was using a Scotch ATG 714 tape gun…zip and you’re done.) You can actually stick it to the grid.
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Yes indeed. I used wet paper towel on my glass tiles I reported on last week (Pre-Release).
Similar to the jig that could be created if you were to want to (hypothetically) engrave M&Ms. You’d need a hole slightly smaller than the cabochon so it rests in what is in effect a divot. I’d do that if I had a large supply to do and they had similar or a relatively fixed number of sizes. Jules’ double-sided tape idea is good but then you have to place each engrave individually as you’ll not likely get spacing, etc. the same from one run to the next. A cut-out jig using wood or acrylic (I’d use wood, or even cardboard or chipboard) will allow you to use that template for placing the text or images in the design file and just tell the GFUI to ignore the cut lines. For the hypothetical M&M jig each M&M resting place has 2 circles - one is the smaller inner circle that is cut out (and then ignored in subsequent executions of the file) and the larger outer one is also ignored in setting the laser but is useful in knowing where the outside edges of the M&M is. That lets you place your artwork precisely knowing it will fit. Then in the GFUI you can drop the whole thing onto your cut out jig.
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Thanks!
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oops. my bad… yes polymer clay is PVC.
“cold porcelain” might work, though. Its corn starch and white glue. Would PVA glue be safe? I did a quick google search but didn’t see a definitive answer.
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Just bumped 4 magnets around the Pistachio I engraved. It was very convex on the bottom, lighter than the glass and the air assist didn’t move it even though it wasn’t held down, just held in place.
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For surface engraving (i.e.- face up) I think they’ll probably stay put without needing any adhesive, since the back sides are perfectly flat. It’s the reverse engraving that I worry about, because the stones are convex and they’ll be balancing on their rounded tops.
FWIW, they’re about 6mm tall at the tallest point… and maybe I’ll just pop a couple in now to see what happens 
I tried one last week and crumbled it to bits.
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Could you use water color paint and then wash it off after?
I don’t know about watercolor paint, but I did read something about using a thin coat of dish soap! My only concern with the latter, is how it might react with the AB coating.
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I’ve used dish soap on pub glasses and it worked great, but have no experience with AB coatings…
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For the “‘reverse painted’ intaglios,” masking and then engraving in stages by paint color may make it easier. That could also be something that requires accurate repeatability, though. If you want to try that, I’d figure out how to use the 12x20 artboard thing first.
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bluetack or whatever color it is now?
For a mold/jig, you can use pretty much anything safe that dries/cures if you put a layer of cling wrap between it and the glass (either non-pvc cling wrap or trim back later). Plaster of paris comes to mind, although spackle would likely do. You won’t get a perfect mold, but it should be good enough to sit in.
Can even put a thin layer of Vaseline on the cabs and bake the polymer clay “jig” with the cab in place – then pop free after cooled…
Another option is silicone rubber paste mold making material – just set the proper sized cabs in it, and pop them free after it sets. This would avoid any possible accidental lasering of the polymer clay and any PVC component…
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Most PVA/PVAc products should be fine, as far as I know, but it’s best to always check the MSDS for the particular product in use in case they’ve added some unusual ingredient.
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Grab a piece of scrap 1/8 inch and laser some different sized holes, then just place a couple of your “stones” and see if that holds them steady enough. If it works you’ll know what size to make the holes for a holder. If it doesn’t work you still got to play with a laser for a few minutes 
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If the bottoms are flat you’ve won half the battle. It looks like they are sized/shaped similarly, but I bet you’ll need a little bit of “give” in your fixture jig. Maybe something like the lil’ mockup I made would hold them tightly enough that they won’t be sliding around, but be flexible enough for slight shape variations.
If this was cut into something thick enough, I imagine it’d also work when the cabochons are sitting on the bed round-side-down.
PS I can’t fix the awesome texturing job I did as I’ve already closed Rhino, but I’m thinking the bendy parts would work better if the grain was running the other direction.
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Double sided tape was my first thought as well.
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This would work great for plain glass cabs, but both the AB finish (front) and foil coatings (back) on these are relatively fragile; I suspect that tape would damage those finishes. In the future I may experiment with removing the foil on some before etching - may try the tape idea on those.
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Here are my initial attempts with the cabs. Clearly, my approach needs some fine tuning, but I learned a few things along the way and that much is good:
Placement shows the order of attempt, from left to right, top to bottom. The first row was done with a wet towel, and I found design placement very challenging with that method. I also realized quickly that finer lines seem to work better, so I switched up the clip art.
In row 2 I started using the dish liquid, which worked very nicely and also afforded easier image placement. By the last two cabs in row 2, I’d also refined the settings a bit more (though they still need more tweaking). I was able to follow in @jamesdhatch 's footsteps a bit, using settings similar to the ones that he used for his glass tiles (low power/high LPI).
Row 3 is where I started playing with reverse etching. These results are still a bit too grainy for my liking, so I’ll keep tweaking settings. Part of the issue may also be how the etching is interacting with the foil. Since I have buckets of culls with damaged foil, I’ll remove the foil from a few of those and try doing some unfoiled engraves to see if that changes anything.
These are some of the larger stones that I have in this style, so they’ve got a decent bit of weight to them. Thus, I was able to go jig-less (which my autocorrect wants to change to “jiggles” 
) for these quickie attempts. A couple of the stones did shift around a little, so I’ll definitely need to sort out the jig concept before moving down to any of the smaller sizes.
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Is the AB coating as fragile as you feared ?
I’m a bit surprised if it is, given that the beads must spend most of their life rubbing each other, and that sort of wear would be a big no-no, commercially.
John
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