The interior trim panels are attached with brad nails. They are driven directly through the face material on the finished panel.

There is a technique to do this without causing damage to the fabric on the panel.
First of all, each brad mail has to checked for a bur on the tiny head. A quick stroke with a file will remove the bur.
Second, Double check before you drive the brad nail straight into the wooden substructure. if you hit the metal casing the brad will bend and then you have a mess removing it.
Third, Use a regulator to make a small opening in the weave of the fabric and place the tip of the brad nail in the opening. This prevents cutting the material.
Fourth, Drive the brad nail until it dimples the surface of the pane fabric.
Fifth, Using a curved needle, pierce the fabric close to the head of the brad nail and pop the fabric over the head of the brad nail.

It is slow and tedious work, but this is how the panels were installed. After a while you will get very proficient at the process and think nothing of it.
I do suggest practicing your first panel install in a none obvious place until you get the feel for the process.

I cut my teeth on these interiors have done more than I care to remember. I you need further assistance , you can message me.

is it going to be kept classic or being hot rodded ?? I would screw strips of steel or aluminium to the wood about 2.5" wide half on wood and half on the open area so 808 panel clips can be used

Thanks for the responses!

Fred, it sounds like there is quite an art to doing it! Thanks so much for the detailed instructions, that's perfect, sounds like you have a ton of experience with them. I'm sorry I forgot to mention before that my customer wants me to use a vinyl/leather hybrid material for the panels, so anything through the face of it will leave holes. I'm sure it won't be the last Model A I work on, so I'm excited to try your method when I do work on another.

Chris, he's keeping the car original, but wants the headliner and interior panels to be done in a vinyl/leather hybrid (as well as the seat). I like your idea, I think that should work perfectly! I just drill holes in the aluminum so I can push the clips through?

The strips of metal work fine, but some panels like above the doors there is no open spaces so you will need to drill the wood out bigger behind the metal to let the clip expand if you are using a metal clip. You can also use "Christmas tree" clips directly into the wood. Make sure they are right as they are hell to get out of the wood. Also the panel needs to be padded right so that the heads of the clips won't show on the face.

if you check out this page of my blog you will see ive done the same on this roadster ...........click the link http://www.rodsnsods.co.uk/forum/topic/whats-trim-shop-week-32177/page114

Thanks Hal, good point I'll definitely need to use Christmas tree clips in a few places to secure the panels. I hate using those things but unavoidable sometimes!

Thanks for the link Chris, that's amazing!!!

ditto about hating the Christmas tree clips. I will not use them. You may want to look into a clip like this fast mount
http://b2b.fastmount.com/products/70/get_pdf/install_guide/en There are many variations of these clips. I have not yet used them but I do plan to give them a try next time I have to attach to fibreglass or wood. I have used snaps on fiberglass doors in the past. It actually worked really well they don't sit flush so I had to counter sink them in a bit.

Fred Mattson Sir, you are a wealth of knowledge. Thank you for sharing with the rest of us

Good luck on your project Amelia!

Awesome, thanks Andy! I've not heard of those clips before, they look a lot nicer to work with than Christmas tree clips!

Thanks for the help, I'll post some pictures when I finish it!

Another idea I hadn't thought of before. It may be worth trying magnets-instead-of-clips

I had a customer want for panels on a Humvee. I had to go with a social type of Velcro.