The best way to minimise the weight of a balsa structure is to use material of the most-suitable density.

Balsa density varies enormously.

 Variation between sheets can cause difficulties, but these are easily avoided. This variation can be turned to advantage, by using material selected to suit the application.

Variation within a sheet is highly undesirable, and often undetectable until you make a cut across the width. Always have some spares, so that you can relegate poor sheets to undemanding uses.

A one-sixteenth by three by thirty-six (inch) sheet of 10 grams weight has a density of 5.6 lb per cubic foot. This is what I regard as "light". A 20 gram sheet I regard as "hard", and a 15 gram as "medium". Much larger variations are met with; 5 gram and 35 gram sheets have their uses.

For other thicknesses, the mental arithmetic is easy, a light half-inch sheet will weigh 80 grams.

When buying, I decide in- advance what sheet-weights to accept, and I take along my electronic scales.

My balsa stock is stored in an orderly manner. Same-thickness sheets are stacked together, with the lightest at the front, and each sheet is marked with its weight ,at the top right corner.