I worked two rows in each colour to give a striped effect.
Chain 32, work 2 treble crochets in the 5th chain from the hook, *chain 1, skip 3 chains, 3 treble crochets repeat from * to last 2 chains, 2 treble crochets in penultimate chain, 1 treble crochet in last chain.
Chain 4, *3 treble crochets in chain space of previous row, chain 1, repeat from * to end, chain 1, work 1 treble crochet in the top of the 3 chains at start of previous row. Finish off yarn and weave in.
Add new yarn, chain 3, work 2 treble crochets in same chain space, *chain 1, 3 treble crochets in next chain space, repeat from * to end.
Repeat previous two rows until it is the required size.