Among lower level collections, many players combine the toy soldiers in order to get two compasses and 1500 coins. Each set requires 2 small winding keys and two small springs to combine it. On the other hand, if you instead combine the books in order to get one compass and 750 coins, and you use one small winding key and one small spring to combine each set, then two sets of books costs and yields the same as a single set of soldier, with one exception. Each time you combine a set, you also receive a clock component to use when combining artefacts. So twice the number of sets created means twice the number of clock parts.