So... i've nailed down what i'm having and am now in the process of CP design...
Planning the following buttons:
P1: 8 buttons
P2: 8 buttons
Start / Coin x2p
Pinball flippers x2
Additional:Shift - P1 hold
Exit - Shift + P2 (I.e P1+P2)
Pause - shift + coin 1 / coin2
Save / Load state - shift + flippers
2 mouse buttons - P1 7/8
Question... when laying out your CP, what horizontal spacing are people using? So, imagining the joy and buttons for each player as a closed unit, and the trackball, I am centering the trackball in the CP (both horizontally and vertically) and having the joysticks on the vertical line with the Trackball center... but do you space out from P1 joystick to trackball and final button center on P2 to trackball or is there some other way to space out horizontally?
May be easier to ask with a diagram...

Should i be ensuring the blue or red spacing is the same? Or should I be looking at something different? Is there a minimum amount of suggested space to the left of P1 stick?
Edit - and before anyone mentions it, i
know 8 buttons is overkill, but for the minimal extra cost of an extra few buttons it will a) satisfy my OCD over having just 7 on each side and b) allow me to use the extras for combos on SFIV etc which i found useful on my fightstick