RE: Brent Good Custom Airframes 106" Yak 54
I got those louvers from an old cowl that had been in a crash. I have made them in the past and there are several ways they can be made. There is an article in the ama magazine a year or so back that shows how to make them from balsa. That is a real good place to start. If you make one master louver you can make copies of it by molding them. When I do it that way I use a little trick from the candy industry. You take corn starch and put it in a shallow tray. Level it off and press the master louver into the corn starch. Put a handle on the master so you can pull it straight out of the corn starch. You might have to play with the moisture of the corn starch so that it makes a good impression of the louver. Once you have pressed in as many copies as you want very, very carefully fill the impressions with laminating epoxy resin. If you have a damn around all the impressions you can fill the whole area with resin and then you will have a male plug that you can vacumme bag a fiberglass layup with. You can also take that male plug and make a female mold by waxing it several times and spraying it with PVA release agent. Build a dam around the perimeter of the male plug and pour resin with microballoons mixed with it. Once the resin has cured pry apart the male and female halfs.
I hope this helps.