It's a wooden model of a 13th century trebuchet (google it if you don't know what one is - there is a particularly good Scrapheap Challenge clip of one in action!). The kit comes entirely pre-cut and drilled requiring only glueing and assembly.
Templates are include for the assembly of the components making it easier to assemble correctly...it's still going to be a bugger to clamp though! I plan on building this kit with my younger brother and sister, who, at their ages have a short attention span, so I intend on making these sub-assemblies then doing the final assembly and testing with them. Updates as and when progress occurs.