Scenario: I am using PowerShell on Windows Server 2012r2 to generate a Root certificate and want to use that to sign a newly created Intermediate and Web certificate in
"Itiverba Self-Signed certificate generator" (http://www.itiverba.com/en/software/itisscg.php) is a free GUI tool for Windows that allows you to create your own CA certificates and sign end-certificates with it. You can export the certificates in PEM, CER, DER, PFX file formats.
It's just 3 lines to encode :
Subject: CN="Testcorp - Private CA"
Basic Constraints: V (checked)
Basic Constraints / Subject Type: CA
Give a file name and select a file format, then click on the "create certificate" button. Your Custom CA certificate is done.