The IGEL OS firmware is provided by https://www.igel.com. The download path depends on the exact version to be used.

 To download IGEL OS 11, go to https://www.igel.com/software-downloads/workspace-edition/ > OS 11 > OS CREATOR (FORMER UDC, DEPLOYMENT TOOL FOR IGEL OS 11) and download OSC_[version].zip

 To download IGEL OS 10 (UDC3), go to https://www.igel.com/software-downloads/software-downloads-former-universal-desktop-and-legacy-versions/ UNIVERSAL DESKTOP CONVERTER 3 (OS 10) (STICK) and download UDC3_[version].zip