The fun of these Star Trek phasers are more shorter bursts with the familiar sound it makes from the TV series.Sounds like you are planning to use some high power diodes. Or, at least, some ones that get quite hot like a high power green.
This Rubie brand has alot of room and could of asked Rich for a bigger sink but I thought having a little more open pocket space inside was better for cooling and if you open the image pic you can see the front sticks out around 1/4 inch by choice. I could of asked Rich to make the whole nozzle and sink one big piece. But with the runs times and power levels I didn't think it was worth it. The plastic nozzle has a series of little holes, not much but just thinking every little bit helps.
I feel very comfortable if I wanted to run the M140 at 45 to 60 seconds. The 520 at 1W a bit less just to be safe.
The phaser with Rich's focus nozzle is made from AL and it screws right into the heatsink itself which is also I believe better heat transfer but it's also only running at 1W.
The battery size that the handle takes is also limited, I thought of trying to fit 14500's but just wasn't worth the little extra capacity.
If you look some other builders they even use up to a 7W NUM44, in a different brand phaser that is limited in size inside and has way smaller heat sink and the biggest battery they can manage is only 2 16340's, and even 2 14500's from one builder which no way they drive that 7W. Crazy over kill.
Again they show a video of lighting some matches, popping a balloon or just quickly igniting some steel wool. That's about it.
Now the Klingon Distruptor Rich has, is a whole different prop. Coming from the main body and handle is a long tube and at the tip is where the laser module will go. It's up to him to just how big of a sink he want's to go with.