I've almost finished my home build version of a proper shoulder mount to fit my EX3. I found that spending 800€ for a Protech ST7 was just to much. Although I thought it was one of the best ones I've seen. I do own a Zacuto but the shoulder mount isn't my thing when shooting ENG. I'd like the idea of the bigger batteries such as the AB or V mount ones.
There were two things I needed. First of all a shoulderpad, second a AB mount to fit the batteries. I found a old broken Panasonic camera on a Ebay like site and bought it for about 85€. It was the perfect donor camera for my missing parts.
After I decided with measurements the mount should have I bought some Aluminum 6mm thick. I cut the plates in halfway in order to bend them in the right shape. I am a lucky person that I have the skill and the equipment to weld the aluminum back together where it was cut. For people that do not please look at the internet en find out about Durafix for soldering aluminum is should do the job as well.
My biggest problem was painting, but that has to do because I just don't have the patience. After a week staring at a bad paint job I brought it for powdercoating.
My total costs.. €85,- for the donor camera, €23,- for the Aluminum, €35,-for powdercoating and €8,- for three BNC plugs.
It's not quit finished cause I'm still missing the sony DC powerplug to connect to the AB adapterbut I can tell It's worth doing it yourself and not difficult at all.
Also two pictures of the left over parts of the old camera with gave me a beautifull quick release adapter. Also I've mounted a rod holder to place a Mattebox... bought at shoot35