Reading the Jerbiton-chapter I was a little confused, that depicting something that has a shape or material bonus only give half the bonus. I was under the impression that the bonus given in the books are not divided into shape and material.
Example: I thought a hazel nut would give the same bonus (devination +3) as a hazel nut made out of gold and this would not differ from something made of hazelwood.
In fact many examples given could be used as both: shape and material.
How about a miniature crown the size of a palm. Does this give you the complete bonus (+5 gain respect) for the crown in you lab project or half of it as nobody can really wear it? But it defenitely is a crown!
I will advise my troupe to use a houserule that it does not matter whether the item in question is depicted or real.
Could this unbalance the game? How do you handle the matter?