[Plugin: Custom Content Type Manager] How to add repeatable fieldset?

Can you clarify what you mean by “fieldset”?

Most fields support a repeatable option, but some do not (e.g. the multi-select fields, the WYSIWYG fields) due to practical reasons or due to WP limitations.

If you are wishing to repeat a group of fields, that’s not currently possible, but it is planned: https://code.google.com/p/wordpress-custom-content-type-manager/issues/detail?id=392 — the proposed “Table” field there is what you want I think: it would enable you to repeat a set of fields (e.g. rows in a table).

I’m hoping to get some funding so I can develop this for the next version: https://www.indiegogo.com/cctm

Yes that is what I mean.