I encountered the same "sealing violation" problem when running in the Eclipse IDE via SweetHome3D.main. Building a JAR worked fine but it is nice to be able to skip that step. The post at [1] suggests that the sealing violation error is due to the version of Java3D installed on my system (OS X Mountain Lion). The solution at that post (the installer at [2]) worked for me and I can now run smoothly from the IDE with no special config.

HTH
Alex

[1] http://stackoverflow.com/questions/1278 ... -3d-on-mac

[2] http://create.ife.no/vr/tools/j3d/java3 ... sx.pkg.zip