Fun LED project

Any of u have a realy small (pocket size) LED project i can make.

I tring to make a UV light pen torch (found one in J-CAR electronics but it was $15)so i making my own. I'm wondering if the UV LED need any special treatment befor putting a powersuply of 1.5v or 3v???
Does it work like a normal diode or does it need more or less resistance ect.???

I have an interesting idea..
normal quartz clocks(not the figital ones, the desk ones) work on a 1.5v battery wich drives a coil and makes the clock run.
the idea is to take the circuit, replace the coil with a lov power, hygh efficency led and put in the place of the coil. replace the 1.5 V batt with 2 small watch 1.5 v batt such as AG13 and it all fits inseide a cheychain.
i made something like this, and it's worked for 15 months from a pair of normal R6 batteries. i think u can make this project with less than $1, and have fun with it!!!!!!!!!