IIRC the cap is just press fit. I left mine off to allow me a little bit more room to work with, and also to make it focusable. I'd love to make a nice RGB chrome pen set like you are doing, but I'd want a better driver/battery combo than the one I'm using currently.
Also, the copper module that I got from DTR is a tad bit too small and just slid inside the host. I made a case positive build, so I fixed two problems by running the case wire from the driver to the outside of the copper module, making a sandwich that keeps the module in place and makes constant contact with the driver. This sounds a bit confusing so I can reword that if you want.
With my PL520 I'm using a microboost and 2 AA batteries.
Hi there! I am quite new to powerful lasers, and although I've owned a few 10mw s in the past, I don't have much real experience in DIY lasers. I love your YouTube channel and I have finally decided to try and build your 160mw pen laser build. I am planning to order the Osram PL450B diode in copper module from DTR's laser shop, and buy the host from jayrob, and I was wondering if you could recommend a suitable driver - as I can't seem to find the Microboost Drive online... I am really eager to get to work on building this masterpiece, but I am in a dilemma about the driver. Does the driver have to be a Micro Boost, and how would I change the current on the potentiometer to 280mA, because that's what you used.