Combining Defender and Robotron on the same machine is a tricky problem, and is the reason we developed the swap panel system.
1 Control Panel, 2 Sticks:
This is a popular design because there has been a control panel overlay and multiwilliams game boards available for a long time. It uses 2 grommet sticks (eg Wico), so is basically a Robotron panel with added buttons.
This design is not very appealing for Defencer fans as the size, feel, and spacng of the joystick and reverse is all wrong.
1 Control Panel, 3 Sticks:
There are two feasible layouts for this.
The symmetric layout has Robotron sticks set closer together, and Defender controls set wider than standard.
The offset layout has both sets of controls with the standard width, but offsets Robotron to the left and Defender to the right. This layout allows for 2 player Joust.
2 Control Panels (3 sticks):
With the quick swap panel system you can have both Defender and Robotron panels with the correct controls in the standard positions, and also the original graphics for both . And then beyond Williams, you can add other control panels too.
This configuration costs a bit more due to the extra panel, and means you will want a storage option too.
Graphics can be tailored in a wide variety of ways. You can choose two different side arts. You could choose an overall colour scheme eg Red/Yellow or Blue/Yellow and apply that to all the panels and sides. Or you could keep each panel to its own standard colours.
The marquee can also be quick swappable so you can have one to match each panel.
Add a specific Joust or Moon Patrol or Sinistar control panel if you want more Williams goodness.