There are loads of coin holders on Thingiverse, and for loads of different currencies - but not too many for UK coins. So here is my contribution. There's even a slot for folded bank notes if you're lucky enough to have some.

I've uploaded the sketchup file so you can adapt it if you want. Don't forget to print at 102% if you're using ABS otherwise the coins won't fit!

I've just uploaded a larger version which also has a £2 coin slot.