OK Easy pods, that can be made and trimmed in 2 hours.
You will need:
- Small sheet of 12mm MDF
- Some thick card, A3 sheet
- Staple gun + 10 or 12mm staples
- Glass resin.
- Some Material to trim with.
- Some Sounddeaning, or flashing tape.
1: Cut 2 MDF collars that will hold the speakers and give you about 10 to 20mm over the size of the speaker.
2: Cut 2 MDF plates that are the same size of the collars.
3: Cut 2 strips of card that are as deep as the speakes plus 40cm
4: Wrap the card around the the collars and staple in place.
5: Do the some to the plates, you can if you wish angle the plate to 'Aim' the speaker
up. I would not recommend aiming them any more
in to the car as the kick panels are angled nicely already. Trim card if needed.
6: Use the Glass resin on the card, use lots so it soaked through. Let it dry, then add some more resin.
Now some would add glass fibre mat to the inside of the pods at this point, I don't just use pure resin and then add sound deadening.
I have just made some of these for a lucky young man on this forum, but with the advance step of using an Aperiodic membrane.
The problem with Pods like this is they lack the air space the speakers need, BUT if you cut out the back you will get cancellation as the sound waves come out the back.
Cancellation basically kills your volume

and frequency response. But Aperiodic design allows the speaker to breath and behave like it is in a 40 liter door but without the sound waves coming out the back creating cancellation problems.
These are some pics of the Aperiodic membrane being added to the already made pods.
The hole the membrane breaths through is exactly half the size of the speaker cone.
First made membrane some a folded pieces of lambs wool with chopped pieces inside.
All wrapped in steal mesh, making sure that the mesh lined up hole to hole so not to restrict the air flow (that's the Lambs wool job).

Finished membrane.

Then it screwed tightly in place in to the pod.

Its backside, the opening is exactly half the cone area.

Sealed and deaden with strips of flashing tape.

Some lambs wool wading.

Trimmed with foam scrim. Just need to fit dowel 'legs' for them to sit on and finish with the suede or leather 

They are a bit messy as they are prototypes and were trimmed then un-trimmed before this!