I suspect that you might have installed them in the wrong 'plugins' folder. Please post the full-path to the 'plugins' folder. It should be the one at the root 'HD' location: NOT the similar 'user' one. Copy/paste this line of code +<enter> into the Ruby Console and see the path it returns: Sketchup.find_support_file("plugins") and then Sketchup.find_support_file("Plugins") If the second version fails you might have a 'case-sensitive' system setup on your MAC which can cause all sorts of issues with Ruby because things like 'Sketchup.rb' and 'sketchup.rb' are seen as two different files ! Please also type this $LOAD_PATH - it should include the path to the HD 'plugins' folder you found above... Also note that SoapSkinBubble's installation-notes ill-advisedly tell you to install it and its subfolder etc into the 'Tools' folder. This is bad practice. I have it auto-loading from 'Plugins' and it loads just fine. Also check that you have FULL [read.write] security permissions [set for 'all'] to the main 'plugins' folder and also its contents, because having less will compromise installations and/or the running of some tools too... Thomthom has a Simple-Plugins-Installer [search Plugins Index via menu item above], once you have installed that from its RBZ file [via v8 Preferences > Extensions > Installer button] it appears in the Plugins menu and lets you install RBZ and ZIP archives for complex tools and also RB/RBS more simple one file scripts... I suggest you use it once you have confirmed your MAC settings etc...