Having built three teardrops, I'm extremely satisfied with the
5x5' 1/8" Baltic birch sheets that I can get in this one-lumber yard town that I live in. (I'm three hours from the nearest Lowes/Home Depot).
The stuff has no voids and you can throw a scrap piece in a bucket of water and it won't delaminate after weeks. I don't recall how many I order for a teardrop, (10? 12?) but the local yard has the number of sheets for me the following week. I think $15 a sheet or some such price. It's really high quality. Brand? I don't know, but I haven't read anyone here having problems with it. The yard here also stocks a few sheets of 3/4" and 1/2" and it too is of the highest quality. Makes AC plywood look like seconds from the CDX pile.
As I mentioned, I laminated nine 3" strips into a 1" thick "bent" piece with an 8"--90º curve. Worked great using two molds and lots of clamps. The stuff really wants to bend (in one direction).
I suspect if you ask your lumber yard (not a box store) to order the sheets for you, it won't be a challenge to get without having to order a bunk.
A lot of people on this forum use lauan plywood for there builds with varying levels of success (great to not-so hot). It's my two-bit theory that lauan is a generic term with great ranges in quality. It's the near- 1/8" ply that Home Depot sells. But I get this so-called knowledge about lauan from reading the posts, not from using the stuff.
Take some pics!
Tony