I have owned my RV3 since 2012 and have been fighting leaky wing tanks almost as long. Not eager to delve into the black Magic required to fix them I decided on a fuselage tank. My plane has too much stuff in the way for a full sized fuselage tank so I designed a cylinder shaped 17.5 gallon than that would be easy to build. I cut the 20 inch diameter end plates using my router and rolled 1/4 inch 6061 T6 bar stock to tack weld around this circular edge. Then rolled a 12 inch wide 65 inch long wrap piece and had a friend tack weld tank. Luckily I found an outstanding welder at Hi-tech fabrication in Shelbyville TN to finish weld the tank and fittings. With only a 0235 in my rv3 17.5 gallons is enough fuel. What I do need is a riveted on flat filler neck for top and unsure how to find part from vans. If anyone has a part number please post. I think all wing tanks use same part that gets riveted to tank skin. I also purchased 5052-H32 .050 aluminum from same shop at less than 1/2 the cost from AS.