Redmine

I am a CAD user who has few experience on management tool / Ruby.

CAD tools are mostly command-driven. which is very easy to learn/use as a user (not a developer.)

In the plugin case, the command-log file can capture the command and the command window let you type in the command.

for example:
to create a new issue: command would like :
Issue.new ( :Name="test1"....)

This way, the user can learn most daily-jobs without to be a ruby-developer.