LED's in tubes?

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Yes.

LED produces very little heat at rated specs so it should be fine.

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To be absolutely sure, you'll just have to test it out, but I think it will be fine at normal room temps. A straw won't do much to keep the light in, but fiber optic cable or a "litepipe" will do it easily. Litepipes are solid plastic tubes that can move light around corners and the like. I believe that digikey sells them.

As for the heat, I ran an RGB LED with a styrofoam peanut pushed over it to act as a diffuser. After many hours, I didn't notice any difference in the light output. I'm sure the wire leads of the LED did a better job of removing heat than could possibly be dissipated thru the plastic enclosure.

Sure. An aluminum tube would be even better from opacity, reflectivity and heat conductivity standpoints.

Absolutely. I did exactly this with about 50 LEDs on a snazzy panel some small company was building where I was a temp. They had this LED panel mounted about 1/2" behind a sheet of transparent lexan with the light pattern screened on the back, and you practically couldn't tell which LED was lit, so I got some straws at the local fast food joint, cut them into 1/2" pieces, and slipped them over the LEDs. Worked perfectly, and they shipped the sucker and started ordering straws, and kept my jig!

Cheers! Rich

For a nice fit you can use heat shrink tubing if you are careful about how you apply the heat. Black heat shrink is very opaque.

So. What is it you *really* want to do ?

There are dedicated 'lightpipe leds' if that's your intention.

Graham

20 ma at say 3 volts (maximum) ? That's 60 milliwatts, or one sixteenth of one watt. Not likely to burn the fingers or anything else!