Buldozer (which is arma3_x64.exe) requires steam client to run.
<steamPath>\steamapps\common\Arma 3\arma3_x64.exe is your buldozer. Replace <SteamPath> with the full path to your Steam directory or to the steam library you installed arma3.
2018-05-29 Warning: for some reason Object Builder requires 32bit buldozer which is arma3.exe, if you try to run it as we described above you'll get a crash. Terrain Builder works fine with 64bit, Object Builder doesn't.
Object Builder, use File → Options and configure external viewer there like this:
-buldozer -window -noLand -exThreads=0 -mod= -noAsserts -nologs -profiles=P:\Buldozer -cfg=P:\Buldozer\Buldozer.cfg -name=Buldozer
Terrain Builder, use Tools → Preferences → Buldozer and configure .exe file path:
-buldozer -window -exThreads=0 -mod= -noAsserts -nologs -profiles=P:\Buldozer -cfg=P:\Buldozer\Buldozer.cfg -name=Buldozer
Please note that Object Builder has -noLand parameter while Terrain Builder does not.
To close buldozer, simply kill it with ALT-F4. Buldozer Controls Keyboard Shortcuts related to terrain editing used with Terrain Builder.
See how to change Buldozer Cursor when working with terrain builder.
ArmA 3 Modeling Buldozer Lighting by HorribleGoat.