The ailerons on the LT-40 are most likely tapered solid balsa stock, appx 1/4 inch at the front and 1/16 at the rear.

You can buy this material in several widths, from 1 inch to over 2 inches, in 3-foot lengths. The front endg is then double-beveled to allow free movement in the hinge line with minimal gap between the control surface and the wing.

The tailplane control surfaces are commonly made from flat sheet balsa, sometimes with holes cut out to reduce weight. Sometimes they are built up of an outer frame of appx 1/4 X 3/8 stock and 1/4 X 1/8 "ribs". Tapered stock as with the ailerons can also be used.

It is also possible to make the control surfaces changeable... Use Pinned type plastic hinges, replace the pins for any given control surface with one long piece of music wire, bent at one end and the bend trapped by tape. (needs periodic inspection) Pull the wire, the control surface falls off, ready to be replaced with another that has had matching hinges installed. (of course.. unclip the clevices on the tailplanes... and the ailerons need brass tube "liners" epoxied in the holes for the torque-rods. (easier to do the tailplanes than the ailerons...)