There is already an Estonian keyboard layout available by default under OS X. Sadly it still has some inconsistencies regarding dead keys and accented characters.
To overcome this issue and make it possible to type some characters frequently needed during server administration tasks, I created my custom cleaned up version of Estonian keyboard layout.
I removed all the ballast, unnecessary bindings and symbols that I never need and made layout similar to the one used under Windows and Linux. It was created for classical ISO-style keyboards with 101/102 keys. These are most common Estonian ones including tilde in the upper left and greater-than in lower left corner.