The best thing you can do is plan to mitigate any damage done. Of course this is easiest by not giving anyone any rights at all, but when you do have to give someone any kind of power try to wall them in as much as possible, so what damage they can do is very limited. Offsite backups that they dont have access to is best for recovery, especially if they have physical access to the site. I know some people will complain that treating everyone like a criminal will encourage destructive behaviour, but at the same time using smart/sane security precautions shouldnt scare away any reasonable people, and those who do react badly to being walled in probably arent the people you want on your site to begin with...

I was seriously considering picking one of these up as i tend to do a lot of low level fabrication (right up to casting noble and non-noble metals) and have yet to find a reasonable and quick method to fab plastics. However looking on the website and reading the review the quality of this product seems extremely questionable, not only did this one unit have 2 major issues within the first day of running (with a complex system like this not exactly a horrid start) but the company itself has a blog post on the front page about how its favorite customer service interaction was one in which the customer decided to fix all the problems on their unit themselves. So my first two impressions are that this unit will most likely be in a state of disrepair in between quick burts of usefulness? I'd rather just submit my renderings to online stores and pay the shipping, etc. simply for the lack of frustration. Now if they got these problems under control i'd have one tomorrow.

Unfortunately the crowns you have gotten probably cost the same for the actual prep, but lab costs have gone way up. The majority of crowns have a large portion of and/or are completely gold. Look at the cost of gold in the last couple years and you'll see why lab costs have gone way way up.