Just got home from work today, and noticed my 18 month old puppy's project of the day, was to get into a bag full of plastic, glow-in-the-dark rocks. Kind of got me thinking about a Halloween prop. Didn't post this under electronics, as that part will be easy with an Attiny13 micro controller. Was thinking about using Great Stuff expanding foam, but not sure about a few critical properties. Haven't used it in a long while, but don't remember it being particularly translucent. Kind of hoping somebody might know if it might pass a little light if it's a thin coat. Second concern is conductivity. Ideally, I'd like this to be quick and cheap. I'm hoping to just freeform the circuit, and and in case the whole mess in foam, with just a slide switch and some sort of connector to recharge the battery.

Great Stuff is the only product I have even a little experience with, maybe somebody knows of something better suited. Figured on giving a go this weekend.

 

I don't think Great Stuff will be translucent enough. Have you considered bubble wrap with the bigger bubbles?

John

 

Great stuff is very barely translucent - might work in a very thin layer with lots of lumens behind it.

Alternative:

There are some nifty products in the adhesives isle of the hardware store. Several are transparent silicon-based products. You could mix in some green glitter (or use silver glitter w/ green LEDs) and/or other "texture."

I've also been able to whip it up - to get air bubbles in it. I use a pair of small kebob-skewers as a makeshift disposable whisk.

 

Had some other stuff dumped on me this weekend, but did finally get to play a little this afternoon.

My first attempt turned out much larger than planned. I rolled up some bubble wrap for a core, about the size of the PCB I figured on using. Figured I could remove some or all of it after the foam dried. Trying to sculpt the foam is a waste, just makes it collapse, have to add more... Found that when the exposed surface seems dry and set, the underneath and inside aren't. Which turned out to be great, since it was easy to remove the core, and left a thinner shell than expected. LEDs shine through just fine. Didn't find the old can of wood stain I figured on using, but will work on that later. Going to do a smaller version tomorrow. Thinking I don't need the core, can just hollow it out, after a good outer shell forms.

 

Had some other stuff dumped on me this weekend

Considering the context of this thread, this is a distressing comment.


Thinking I don't need the core, can just hollow it out, after a good outer shell forms.[/quote]Sounds like a variation on slip casting.

 

Considering the context of this thread, this is a distressing comment.


Thinking I don't need the core, can just hollow it out, after a good outer shell forms.

Sounds like a variation on slip casting.[/quote]

Yeah, wasn't even trying for that one. Mom needed her cordless phone repaired (told her to just buy a new one), but messed around to see if it was done. Little brother got a job doing demo for a remodel on a hotel, left some pretty cool looking Gentex fire alarms (strobe/siren), had to hook one up. Marked 24 volts, worked fine off of 12V, even 9 actually.

I've got four new models hardening as I type. Should be another 10 minutes or so, then scoop out the goo like a melon.

Haven't really settle on a lighting scheme as yet. Yesterday, I just used an RGB fader PCB I had laying around, with 2 green and one amber. Color was mostly okay, might just modify the code so they are all on a little, no black. Anyway, its time.

 

Little brother got a job doing demo for a remodel on a hotel, left some pretty cool looking Gentex fire alarms (strobe/siren), had to hook one up. Marked 24 volts, worked fine off of 12V, even 9 actually.

Yup. The strobing frequency slows down since the charge is slower, but they will indeed keep flashing.