Mallets are basically hammers with heads that are softer than steel.
also see Project:Mallets for some DIY mallet ideas!
|DE: Schreinerklüpfel, Klopfholz,
|(large) woodworking chisels
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Improvised Light-Weight Mallet
Lukas made a simple wooden mallet from an old bedpost before we had a real carpenter's mallet. Due to its light weight it is still useful for driving small chisels, though! Making a similar one yourself is very simple, but the grain direction of the wood is not ideal for hitting stuff...
You should be able to find it in the wood workshop.