That said, ... ^^^
I have made a few fiberglass subwoofer enclosures for an OEM look in the trunk. It isn't hard if you follow someone else's DIY picture guide. Here was the process:
1. Throw some plastic into the void to be filled.
2. Paint on a release agent.
3. Add a few layers of fiber and resin.
4. Remove and continue to glass the inside of the shape.
5. Buy a flush-mount ring and use temporary supports to place.
6. Stretch a piece of fabric over the flush-mount ring and attach to the fiberglass tub.
7. Add more fiberglass over the resin-hardened cloth.
8. Basically done.
For a pod, ...
1. Make a block the same size as the ScanGauge.
2. If the pod will sit on something, you can lay up the fiberglass base to get the contours.
3. Add the block to the base.
4. Use fabric to get smooth lines.
5. Glass on top of the fabric.
6. Sand, Bondo, smooth, whatever.
7. Paint, texture, carpet, whatever.
I would suggest trying to get some type of "frame" that you can use to box in the ScanGauge compartment. You won't be able to get super smooth around the display using only fiberglass. Maybe you can find a rectangular piece of aluminum or plastic that will nicely trim out the display opening?