Here is an fairly simple way to make an air filter.
I've made a few and it doesn't take much time or effort.
Here's what you'll need:
Plastic tubing (I like the Evergreen 1/2". You can use what diameter works for the size you're making)
Flat stock (I like .010 or .020 Evergreen. Looks close to my eye)
Top for the air cleaner (Old hub caps will work or you can cut out one)
Bridal veil (I use black and spray it silver, if needed) Got mine at the cloth store.
Determine what diameter air cleaner you want. Then decide how high you want it.
The tubing will act as the filter element.
Then cut a piece of tubing, that diameter and that height (as shown)
Next, cut a piece of bridal veil about the same width as the piece of tubing you just cut.
Cut it a bit longer than the circumference of the tubing.
(You will most likely want this to be silver or black to replicate the wire mesh of the outside of the filter element)
Next, lightly put a dab of glue on one spot on the tubing (all the way across)
Next, attach the bridal veil to the tubing and let dry a little.
Then you can wrap the BV around the piece of tubing as below, use just a bit of glue to attach the BV in the same location where you first glued it. It will overlap, but you can trim it close so there's a small seam. Just turn that toward the firewall when installing it later.
Be careful not to pull the BV too tight.
You can use a sharp X-Acto or scissors to trim away the excess, just be careful not to trim off too much.
Next, you'll need a top and bottom.
For tops, old hub caps will work. You will need the top and bottom to be just a bit larger in diameter than the filter element.
Then, drill a small hole in the center of the top for the stud that holds the wing nut and keep all this together.
On the bottom plate, you'll need to work that out so it'll attach to and clear the carburetor. Still, easy to do, just be sure it's a little larger diameter and centered. I drill a small hole in the center of the carb when everything is lined up and put a small rod in it to align everything at the end. That way you can remove the air cleaner if needed, or it can be glued.
Here's some finished ones and an AMT stock car one.
Here's a couple of my air cleaners that I made.
Hope this helps & have fun !!