As a long term user of TinkerCAD I literally have several hundred designs in my workspace. Dozens of these designs will never be used again, so they are unnecessarily taking up valuable space on the TinkerCAD servers.
Whilst I'm keen to tidy up the workspace, selecting and deleting designs one at a time is very time consuming. A couple of ideas for possible enhancements:
1) Add a simple checkbox for each design on the workspace, allowing multiple designs to be selected for deletion in one action.
2) Add an attribute to each design to define an auto-delete date. If designs are needed long term then that attribute could be set well into the future (or cleared for the design so that the deletion algorithm ignores it). This attribute could be modifiable via the design properties.
In the event of auto-deletion, perhaps the TinkerCAD system could send an email to the user 7 days before the deletion takes place, giving the user the option to extend the lifetime of the design (thus removing it from the pending deletion list)