There are various kinds of balsa wood both in domestic and international markets for your selection. And balsa sheet may be required when you make models, like wood aircraft. You'd better create a balsa skin by joining sheets together. However, it requires patience and techniques though it seems quite easy. Your patience and techniques determine your working results actually.
Frankly speaking, balsa wood sheets vary in thickness. It is not a good choice to join countless sheets together at random. You may spend time to match thicknesses and the direction of the bend. Otherwise, you can't ensure the balsa wood skin you provide is perfect or just qualified.
Then, you should press sheets together on a table. You'd better use a razor blade and a straightedge but not a knife to trim the affected edge if the gap is bad. Generally, only the razor blade has the sharp quality that you need. You may use a sandpaper to sand the balsa sheet carefully after you cutting it. It is not necessary to use the razor if the gap between two sheets is minor since a long sanding block is proper.
There are various kinds of glues both in domestic and international markets. You are advised to choose the lacquer masking tape to tape sheets together. Apply the tape in short strips with gaps between, then fill the gaps with more tape. Turn over the balsa skin you've created with the sheets. Keep the first sheet on the table and let the rest hang from the edge. Well, it opens up the first join and you should glue along the join with glue. Pull your sheet onto the table as far as the next join and fill it with glue. Now, you see, you should repeat the process until you glue all the joins. Then use a knife to remove the excess glue.
It may cost two hours for the glue to dry. You should remove the tape and ensure that there is no tape residue on the balsa skin. There will be a warp on the finished skin of the balsa sheet. Don't worry. You can spray some ammonia water to restore the original shape.