Here's a very simple and clean DIY counterweight solution to add onto your 15mm Video Rigs. This tip comes from Jason and he shows us how a Balance Weight typically used on telescopes will clamp nicely to any 15mm Rail. [Thanks Jason]. He's using a Meade 1422 counterweight, but i'm guessing there are other versions that may work as well. Check out the products via eBay (click here).
I purchased a few Vinyl covered Scuba Dive weights to be used as a DIY counterweight on a Gini Rig (seen here), and also ended up also using them for the DIY Crane (seen here). It's much more expensive than basic round Gym weights, but they are smaller and have a much better aesthetic appeal when mounted to a rig. I did of course have to drill through the Dive weight to mount a 15mm clamp, so there's a little DIY involved with that.
It comes with a solid metal bracket, has several through holes, a slotted center, and quite a few 1/4x20 threaded ports to make mounting the brick to your project much simpler. I'm not a fan of the spray painted logo, but it's easy to sand off for the complete flat black finish. I have two here that can be stacked together for one of my larger Jibs. (click here to find the Opteka Weight via eBay).
Not a cheap solution since i'm using a rail set and clamps, but something like this can be done using other techniques. It doesn't take many of these large washers to add up to about 8lbs. and the further you can position the weight, the less you'll need to counter the weight in the front. Much easier than carrying around workout weights, making this portable Jib truly portable. I guess something like this can be used in the rear of your Shoulder rig too, if you can live with the aesthetics.