If you like to learn by watching, we have a nice video about using these components:
The general idea is simple:
Any design file (
.castle-transform) can be loaded (instantiated) by
TCastleTransformDesign). To create such design file, with any component as a root, you can use:
Menu item "Design → New Xxx (Custom Root) → Xxx"
Or save any component to file using "Save Selected…" command (right-click on the component in hierarchy).
Then you can reuse it:
"Edit (Copy Here) Referenced Design" (detach from the referenced design file)
"Revert To Referenced Design" (use after "Edit (Copy Here) Referenced Design"; this removes all the children and reverts back to the original design file)