I do realize lots of folks like flat foam board, so if you have a Walmart handy, keep in mind you can by online and have it shipped to the store for free (normally) and pick it up after arrival. Lots of store do this also, including the Dollar Tree store. I got my last load of Ross foam board that way at the local Walmart, and a box of Adams Readi-board at the Dollar tree store. I also go to the local Home improvement warehouse stores for various thickness of insulation board since there are more than a few ways to build aircraft from thick, or thin foam sheets. One method is called horizontally laminated construction, and the other is often called vertically laminated construction, among other names. Various RC websites speak of the methods used to make any aircraft fuselage, or wing real, or imagined by making a center outline and adding smaller and shorter layers to it until the desired thickness is accomplished. The aircraft outline is often cut out in the center since that is where the RC hear will be installed and the next outer layer is also cut out to give a deeper, or larger space when needed. Other layers are often not more than filler for the desired fuselage, or wing thickness.
Then the foam shaping begins as if whittling, sanding, cutting, or otherwise shaping the foam. Reminds me of old style wood carving except foam is used. Once the lamination work has started, it is often practiced to leave off the final layers on the outside of the fuselage until the RC gear is installed, tested, and the hatch plan decided upon. Most access hatch plans are on top, include the canopy, and are plenty long enough to make battery replacement easy and adjustments to RC gear possible without tiny fingers. Any finishing work like putty/spackling, paper, and painting are an individual preference and there are many options.
As to foam sources, have you considered roadsides, trash cans, packing foam, foam dinner plates, and foam drink cups? I help pick up foams of various types while I travel back and forth from town since the city dump is a bit more than halfway into town. I sometimes see city dumpsters with large foam shapes from shipping boxes, and I recycle foam drink cups. When I need stiff, thin foam sheets, I buy a package of foam dinner plates for $3-5 dollars and get hundreds I can cut into 5"x 5" squares without a lot of effort. The foam panels work well on fuselage, or wing frames done in various ways, but will remind old timers of balsa wood airplane build-up kits, even if I'm not using any wood products. Sometimes I do, but it may not be balsa since it is a tad pricey. Just some ideas for those living in areas with few, if any local stores with good foam sources.
