Here are the basic media you need to start Windows 10 OSD.

Windows ADK RC for Windows 10

https://msdn.microsoft.com/en-us/windows/hardware/dn913721(v=vs8.5).aspx

(Note: it will be located at the last part of the page)

Windows 10 Insider Preview ISO April Update

http://windows.microsoft.com/en-us/windows/preview-iso-update-1504

Windows 10 Enterprise Insider Preview

https://www.microsoft.com/en-us/evalcenter/evaluate-windows-enterprise-insider-preview

MDT 2013 Update 1 Preview

https://connect.microsoft.com/ConfigurationManagervnext/Downloads/DownloadDetails.aspx?DownloadID=57061

/mike