Sharepoint designer is not allowed. The forms must contain fields with references to list items but may contain custom asp controls as well, which we whish to use later in the process. The target isn't always to replace the original new, edit and display forms but to create extra forms too. Currently, we create custom forms by copying the existing base forms and edit them by hidding the zonetemplates and add our custom fields below. It aint the most elegant way, but at the moment the best result we have so far.
What about security questions with custom forms? We have reasons to believe that the security will be more complex if we build custom forms. Custom forms are opened by ribbon buttons, what about the security? How can we narrow down the acces to such custom forms to authorized personel, groups, users?