I just came across a post that answers this question. http://revitscratchpad.blogspot.com/2011/05/fake-revision-clouds-in-revit.html
First use the revision cloud tool to create the shape you want. But before closing the revision cloud tool, select and copy (Ctrl-C) the cloud geometry. Then click the X to close without saving. Now you can Paste-Aligned and the cloud is created as detail lines. Clever, no?
I tried to make a filled region the same way but it didn't work for me. Pasting the cloud geometry only shows as a rectangle. Maybe someone has a suggestion?
Hope this helps,
Bill
Bill Fowler NCARB
Revit LT Suite 2024
Mac M2 Pro Mini, Apple Studio Display; w/ macOS Ventura, Parallels 18, Windows 11. 32GB memory (Parallels assigns 16GB for Windows virtual machine)
Solo Architecture practice in residential and small commercial design.