If you can find one, the Sig Kavalier! Lot's of detailed instructions, covers all the building techniques including a tapered wing with leading and trailing sheathing, a "box" fuselage and plenty hand shaping of balsa stock (wing tips, leading edges and cowl fitting). Main wing alignment has a unique built in (part of the wing ribs) alignment tool and needs to be constructed over a building board. Purchase a few extra 3/32 sheets of balsa as the finished fuse looks better planked lengthwise. True "builders kit" but not overwhelming and I've yet to master it's flying capabilities. Use the "Carpenters Rule" (measure twice, fit dry and then glue) and take your time installing and aligning the wing mount dowels (just a tad' tricky). Looks like Sig's used two different cowlings in thse kit's. The flimsy "white plastic" and the heavier (yellowed) stuff that almost looks like molded fiberglass (it's plastic also). Take your time cutting to fit your engine (kind of unique 45 degree install) and anchor those cowl blocks. Easily rigged and large compartment for elecronics. May want to purchase a servo tray as none provided (can be built). Metal landing gear is tough as nails so "re-inforce" install. Did I tell you I like this kit? Honest this is a good, streightforward & logical build. Just take your time!
Hope this helps!