I've mentioned somewhere before that I was making different trigger plates for my Ballard builds, here's another such project.
I'm sharing some proprietary photos of a few designs we came up with so it is a secret...  
The striker assembly and the CC trigger design is ours and we did a PP but the market will never justify production- making it a joke.

I had made a set of CC trigger for this breech block and used it on this particular rifle (a 40-90BN).  It works OK but not a favorite of mine, setting the triggers requires an extra step that sometimes I forget...  After wiping, and loading, lying prone in the grass, focusing on your next shot, set to touch things off and... crap, forgot to set the trigger... often times I forget what rifle I brought to the dance... whereas a single trigger - give it a jerk and away things go.  Can anyone relate?

The first photo, is starting with a piece of 3/4" by 2.5" hot rolled bar stock.  I flycut a radius on the bottom of the trigger plate, followed by flycutting each side of what was to become the trigger plate taking it to thickness.  I then roughed out my width of what will be the lug for holding the trigger, scribed a hole for the single trigger location, drilled and tapped this.  I flipped the material in the vise and duplicated the mill work on the other side.  I use the mill to rough things to scribed lines followed by file work to fit the plate to the breech block.   
The single trigger shown is one I use for fitting, a final design will be made later to fit this particular block.  You'll notice the protruding setscrew that engages the sear, I'll probably use a similar method, just not quite as long of projection.
The last pic shows the plate clamped in position via the vise, and it functions.  Now what's left is filing, fitting, a small trigger spring, and some screw holes.
Greg

Thanks Vall,
The one shown is the third version where we rotated the tigger sears to minimize the height of the trigger assembly.  To answer your question, now that I have kind of figured out the process, about 10 - 12 hours.  To get the first one figured out... probably 40+ and a fair pile of scrap.  Here's where they start from a piece of flat bar.