Is it possible for a company user to fill out some fields (always the same) in a form and send it to a client for that client to be able to complete the remaining fields (always the same) without editing the already completed fields? I thought about setting some fields to read only upon update, but Validation rules do not have the option for read only.  Another option could be company users have access to edit some fields but public users can edit others.

I am really trying to find a workaround for Estimates.  I have been using Books Estimates but we desperately need the ability for users to select which options from what we give them, they want to approve.