I f you can't get a set of wing cores, try to make yourself or at least the root and tip emplates along with a fre hand sketch of the wing.
You easily make the root templat by copying the root shape and deducting the I believe is the 1/16' or 3/32" wing sheeting thickness. The tip is a bit more complicated as you may have to cut off the wing tip to expose the tip rrot and make the tip template. Once this is done send copies to "Wing Mfg and have cores cut out.
Or go to someone who can cut you cores.

Let us know how you do.

Orlando