Any ideas on make struts for a .40 sized citabria?

Hobby Lobby has these you could start with if they are long enough.

http://www.hobby-lobby.com/struts.htm

Machined Hardwood Struts
Much cheaper short pieces (19") of the Machined Hardwood Struts!

These are cut by machine into very smooth surfaced airfoil shapes. The hardwood is either linden or lemonwood. Length of each strut is a little over 19". The chord-width of the three sizes in inches are: 3/8", 9/16", 1-1/16" respectively. These are hardwood and can be used for structural purposes whereas the standard airfoil shaped hollow aluminum tubing types of struts needs internal bracing.

If they are too short, for longer ones I took some spruce and roughed them in on a 4 inch table saw then a little sanding and they are good.

Use K&S streamline aluminum tubing. Solder an "8-10 stud" electrical ring terminal to a 2" - 3" length of music wire, then JB Weld the music wire inside the tubing. Join the 2 pieces of tubing together with JB Weld and file/sand smooth. The8-10 stud ring terminal is an excellent size for a 4-40 bolt fastened into a blind nut in the plane. The struts are very strong, yet very light.