Edit: When I linked this post on TMP, Col.Campbell (hi, Jim) commented on the name 'mangonel' being applied to this type of siege engine, thinking it should be called a 'trebuchet', specifically a 'traction trebuchet'. For some reason, I've always called them 'mangonels'. Luckily for all, both of us are right, and Jim posted this interesting link about the "Torsion Mangonel Myth" explaining why.
Before I get to the models, let's get the big issue out of the way. I know that throwing engines were not used in field battles. However, artillery, in any period, can be great table-top fun. I know because, I have a couple of onagers with Frankish crews (Gripping Beast Normans range, I think) which have seen the table a couple of times.The basic design for these models is taken from various sources including pictures and models of Chinese mangonels. The scale I can only call 'table-top scale'; they were made to look just big enough to look like practical pieces of siege equipment.
Neat little models that cost next to nothing. Something from scrap.