I made some different Squirrel kits up to give some different construction methods a try.
In the pictures you can see two prototype kits. One has foam parts and the other has interlocking balsa parts.
There is some satisfaction to having interlocking parts. Higher precision and more of a sense that you have the right part in the right place.
But it doesn’t favor building right on the tissue. It’s harder to get the alignment if your sticking the pieces down. Without interlocking parts, it is much more forgiving as to where you stick the pieces to the tissue.