In order to create stuff without having to click on it all the time just duble-click the icon. Let's say you want to create a triagle. intead of clicking in the LINE icon 3 times, you double click once and draw your line.To terminate just click again!
I think the best way it to go to the tree and select your part body, right click COPY and then hit PASTE from edit MENU
The copied body part will be called "Copy body part 1" and will be shown in your tree.