After laying up flat pieces of fiberglass on the table, I cut them into strips 1 1/4 inches wide with a band saw. Next, they were trimmed to length from the top of the door to just where the radius for the bottom was to take place. I decided to round the bottom corners, but I could have made them square also. The strips were set in fiberglass bondo and 90 degrees to the door. I cut a piece of a bondo spreader and sanded a radius on one corner and then ran it along the fiberglass bondo where the strips meet the door. This gives a nice filet on both the inside and outside. After the bondo was set, I lightly sanded the fiberglass bondo and then laid two layers of fiberglass mat on the inside and the outside. This makes a very strong addition to the door.
To get the rounded corners, I cut a piece of 1 oz. fiberglass mat that I laid up , and then curved it around on each corner and attached this with fiberglass bondo and held it in place with a couple of spring clamps. This was done prior to adding the two layers of fiberglass mat. This way both sides can be laid up all the way around the subframe at the same time. When everything was cured, I trimmed the excess with an air saw. I use an air saw because it is small, easy to handle, quick , and a lot easier to control. With the excess trimmed, I took a long board ( sanding block ) and dressed everything and made it square.
This picture shows what it looks like after sanding and smoothing.
Now I took the fiberglass that was laid up in the 2” angle iron and cut , trimmed, fit, and attached with two sheet rock screws for alignment. I made cardboard patterns for the corners and then transferred these to fiberglass mat that was laid up earlier. Here you could use two layers or three. I used two layers. These will be held in place with fiberglass bondo and a couple of spring clamps.
This picture shows everything in place using fiberglass bondo as the “ glue “. Notice the clamps holding the corners and the sheet rock screws holding the long pieces. Also notice that I added a couple layers of fiberglass at the top of the door to bring it closer to the same height as the sides. Where the angle fiberglass pieces bond to the straight pieces, there is a natural rolled space, this is a great place to gain additional strength by filling in this area with fiberglass bondo. After everything is set up . use a sanding block or small electric sander, and smooth everything out. When the finish work starts, I use ultra lite bondo to work everything smooth and nice for primer.