I have and my next project is to write up the process. I've told a few forum members what I am up to. Basically, you can retrofit the click drag on to one of the simple friction drag reels I show how to build.
Simply create a ring for the back plate - exactly like
Joe's reel he posted photos of. This creates a cavity for the click mechanism. If you use 1/8" thick material and an 0.32" thick ring over it, you'll have a 1/8" deep cavity for the mechanism. The "gear" can be cut from sheet brass as can the pawl. Steel works too. Music wire makes a better spring. I've also purchased several 100 feet of spring steel of the right dimensions that I'll be offering.
As for adding weight - of you do the above, the spacer ring could be made of brass - either 1/8" thick or several layers of the thinner material. That adds a nice amount of weight. You can also make the spool out of brass rather than Delrin for more weight. I would recommend bushing the brass with a Delrin sleave though - Delrin is just too nice for a low friction/low maintenance bearing for the spindle.
The devil is in how to make the clicker wheel (gear) and pawl and attaching them. That is what I am working on now. I've gone through 6 designs/experiments and finally have it figured out.
cheers,
Michael