JP,

There are so many things involved that a picture, alone, wouldn't tell you much...

If you are flying 1/2A, have you tried using a much larger bellcrank than usual? The idea is that our hand moves the same angles, and needs some space between the lines for us to hold it, whatever size the model is. If you've flown "larger" models with the classic 3" bellcranks, you should have some experience with the 'natural feel' you can get with that and a comfortable size handle.

1/2As usually show using about a 2" plastic bellcrank - if your handle is about standard size, think how much quicker and further that little bellcrank would move with your 'natural' control input angles at the handle. Sure, you can move the lines at the handle closer together, but I prefer the broader range with a wider line spacing at the handle - combined with about a 3" bellcrank. 1/2As don't have to be too touchy to fly enjoyably...

(Actually, I prefer to build my own metal bellcranks, too, so I'm not limited to what is mass-produced, or offered by specialty suppliers. )

However, general suggestions:

Make some provision for adjusting to neutral. The old EZ-Just handles had a cable passing through a sorta "buckle" for this. A comfortable neutral hand position is very nice to have... If things get scary, you can relax your hand and know where the model should be.

Finger troughs on the grip usually aren't worth the effort. It is better to form the grip to rest comfortably in your hand along the second bones of your fingers, when you pull the handle like the model does. E.g., loop a string through the connection points, set it over a doorknob and pull about 10 lbs of so. That's more than you'll likely fly, but if it's good there, it will be good at lighter pull loads, too.

Separation at the handle between the line connectors? Figure that if they are the same distance apart at the handle as they are at the bellcrank, the bellcrank moves to the same angles as your hand. It is usually better to attach the lines wider apart at the handle than at the bellcrank. You can control how far the control surfaces move by using a "shorter" radius at the bellcrank for the pushrod, and a "longer" radius at the control horn(s). Most of the time, you won't need the elevator (and/or flaps) to move as much as 25° each way from neutral, so juggle the bellcrank and control horn radii to get no more than about half your wrist angles. You can always move your hand/wrist/arm a bit further if you need. THAT is much easier than trying to tame a too-twitchy responding model by brute force.

Enjoy your efforts! It's always nice to create the stuff you use. Too many guys are missing out on that, today, IMHO...