Just a pragmatic to do sample:
-Right click your Project (under Solution), select "Manage nuget Packages..."
-In Menu click Browse Tab search for "wpftoolkit", select "Extended.Wpf.Toolkit
"
-Install it!
-Right click in your User Control Toolbox, select "Add Tab.." and name it "WPF Toolkit"
-Right click on the new "WPF Toolkit" Tab, select "Choose items..."
-In Menu click "Browse..." Button, look for nugets DLL folder, select all
"...\packages\Extended.Wpf.Toolkit.3.5.0\lib\net40\*.dll
"
Ignore Warnings about some DLLs may not containing user controls!
Ready :)