These could be done with custom made “CMS” for your needs. If you have some knowledge on PHP /MYSQL techniques these can easily be done.
A simple idea is to create tables you need for user info, tech drawings and user page ( which can also be included in user info )
And when the user logins to your site he would be “redirected” to their page. If he tries to access another page with a different user_id assigned to it he would be taken back to his page or get a message that he can only access his page.
I hope that I have helped you with this suggestion.