I did mine it was very labor intensive. It took me about 24 man hours to wet sand,compound, finish compound and wax. Typical shop time is at about 100.00/hr X 24 hours= 2400.00 which is just labor. Now add the cost of materials right at about 400.00. Mine is an 18' Skeeter just did the top cap and sides. The wet sanding is done by hand period I started with 800 grit sandpaper then 1000,1500,2000,and finally 2500. That is 5 times over the top cap and sides. The only machine used was a buffer for compounding and finish compounding over the top and sides. This is why most places don't do it unless a major repair is being done.
Who ever said nothing in life is impossible.
Never tried slamming a revolving door.