Dynamic no of columns in a child table

I am still figuring it out - still in the meantime if someone has tried this out please help me save my time. I am adding a doctype which is a child table to another document. I select the date range from parent doctype and in the child table I want to add those many number of columns as that of date range. Is this doable? As I remember hearing in Developer WS that there is limitation on usable width area?? Any pointers pls?

Child tables are not dynamically configurable.

You are better off making an HTML field and using HTML/JS to build your widget.