I can help you with both the kit and the clay...
first like any other model you need to have all your supplies. (1) bottle quick sealing glue, (1) roll of thick tape, perferably duck tape (1) comfortable chair (1) trash bag
(you may need a friend to help you with this)
Step one: wait till the girlfriends asleep. While her lips are closed apply the quick sealing glue to her mouth. (This is important so she cant scream)
Step 2: step one should wake her up quickly so be prepared when she wakes up with the roll of tape. Quickly apply tape to the hands, wrists, elbows, feet and knees
Step 3: place the girlfriend in the comfortable chair and apply more tape to upper arms and legs.
Step 4: with the girlfriend watching throw the model ship in the trashbag. Now in a calm voice explain to the girlfriend that the same fate awaits her if she doesnt get with the program. (you may want to wait for a cooling down period before removing any tape, I recommend atleast 24hrs)
This should help you with your problems..... :)
Should you actually feel the need to take this course of action I absolve myself from any legal reprocutions :)