I don't know much but I use the heck out of commands.
Here's the code:
if (Contains (plate,lump of clay)) {
msg ("The clay is already on the plate")
}
else {
MoveObject (lump of clay, plate)
msg ("You put the clay on the plate....</br></br>")
ShowRoomDescription
}
and game:
You don't have to have either items in inventory. You can add 'if' script if you want the player to take first.
Add the response you want and it will over ride the 'done' response.
Oh yeah, you can make the plate a surface container and it will show the plate(which has on it) clay.