Problem: Our cats keep opening our lever-handle doors. Too smart for their own good!

Analysis: They jump up, grab the handle/lever, and hang on it, wiggling around until the door unlatches & opens a bit. Then they pull/push the door bottom and get out.

Solution: Design a device that keeps the handle from coming down - only allow it to be moved up to open, which cats can't seem to figure out (yet!).

Already been done?: Yes, commercial versions are available, as well as some other Thingiverse designs, but all seem to require removing the door knob, installing a big lock-type unit (some with break-out pieces), then re-assembling the knob - a somewhat painful and semi-permanent solution, some of which may damage the door or finish. We've tried and installed a few types. But, we need to move the lock from door to door easily, as we move cats around. What a pain!

Solution Design Criteria:

• Slip-on, slip-off easily - no removing/replacing screws for installation
• No damage to door or finish
• Downward pressure on lever uses door jamb to prevent handle rotation
• No restriction on upward lifting of lever to open door from either side
• Same part can be used for either left-side or right-side levers on doors (symmetrical)

Note that this design relies on pressure against the door jamb, so it MUST be installed on the door jamb side of the door. However, it is symmetrical, so it can be installed on either right or left side handles.

The part is designed to be used with additional adhesive-backed felt pads to protect the door finish, and some adhesive-backed foam strips to hold the part against the lever as it rotates while opening. See the section "Adding Pads" below.