I wanted one that really "worked" and looked good, so I made my own. The project was more about learning electronics than anything else, but in addition to the new understanding of how to build blinky lights, I ended up with a pretty neat toy. I modeled mine after a Hero (that means it was used for close-ups) ROTJ Blaster prop that recently sold on ebay.
The blaster build consists of 2 sub-projects : building the electronic effects, and making the gun itself.
The circuitry is pretty basic and was my first real scratch-built electronic project. It involves a 555 IC timer circuit to trigger the sound and LED effects, and a 4017 decade counter chip to make the LED chaser effect seen at the rear of the gun.
The chassis of the blaster is made from PVC and aluminum tubing, some sheet aluminum a real scope and grip and a few other doodads.
Step 1: Electronic Effects Overview
In order to keep the effects synchronized and of a consistent duration, each trigger pull will set off a one-shot timer, which will trigger all of the effects for about 1/4 second, and then turn them off even if the trigger (switch) is held closed.
The Laser diode, Red LEDs (muzzle flash), and the sound effect module, and the blue LED chaser are all turned on by transistors that are triggered by the timer.
The LED chaser effect consists of another timer set up as a normal oscillator, which is driving a 4017 decade counter chip. The decade counter lights up each of the 10 LEDs in succession.
You can see the effects in action in this video: