Looks like you're doing great so far. Here's a few tips when applying the fiberglass mat.
Tip #1 - Don't try to do all four sides at once because gravity is your enemy. I do three sides then flip after the three sides set up. Glass side four separately or, do two sides at a time. Not sure if you're following me.
Got it!
Tip #2 - Don't leave a smooth edge on your fiberglass mat. Tear the edge of the mat with your fingers so the edge is rough. This eliminates the seam where two pieces of mat make contact. I usually cut all of my pieces several inches oversize and then hold them tight to a straight edge while I tear them. The edge of my table saw works good for a straight edge. Again, not sure if you're following me.
Got it!
Tip #3 - Start and end all your pieces of mat in the corners. This also helps hide the seams. Tear along all four edges of the mat for the box bottom and only extend this layer of mat to the radius as well.
Got it!
Tip #4 - sand like a madman.
I'm sure this will be the most fun of all.
Tip #5 - Don't skimp on fairing compound over your final coat of mat. The best fairing compound is probably Poly-fair but I don't think it comes in anything smaller than a five gallon bucket. You might have to improvise with a different surfacing putty. If you are generous with your fairing compound and sand like a madman, you will be happy with the end result.
More sanding.... I should be pretty good at this by the time the project is done. Any recomendations for fairing compound? Your right about the 5 Gal.
Tip #6 - When everything is sanded and prepped for gelcoat, consider having the gelcoat sprayed by a local shop. Spraying produces a superior finish. Also, the cost of materials to apply the gelcoat yourself might exceed the cost of having the gelcoat professionally applied. The shop you hire to spray the box probably already has a supply of gelcoat. Because the box is small, it won't require a lot of labor or product to do the job. It will also save a great deal of time spent sanding and sandpaper expense. The cost of a five gallon bucket of gelcoat is now about $200 and you can probably have someone spray the box for $100 - $200 including materials.
I know there's a certain amount of pride that goes into doing the entire project on your own. I have a workboat that I built from a kit. I like to do all of my own work. If I think someone else can do the job as good or better for less money, I'm not afraid to farm some of the work out.
I will look into that.... I actually called one shop when I first took the sink out to give me a price to do the whole job... I guess they must be really busy.... they still haven't given me a price.
They called a few times and asked a bunch of questions but never followed thru.

Storm