I made my first batch of cold-process soap earlier in the year – it took FOREVER to trace, but we’ve loved the resulting soap so I need to make some more.

Ever since I made that first batch, I’ve been on the look out for what I can use as moulds this time around. Last time, I had two old food trays for bar soaps, but when I ended up making a lot more soap than I’d originally intended, I grabbed whatever else I could find – some shaped fruit trays (small hand soaps), an old round ice cream tub (too wide when sliced into discs so had to cut them into semi-circles, which was a bit odd) and the square edged plastic bottles the olive oil had come in (nice size hand soaps, but it was awkward to get it out). (The latter two can be seen in the picture.)

All sorts of packaging has been subject to my “would it make nice soap?” eye. A few weeks ago, I was reading about someone else’s soap making on Simple, Green, Frugal and she mentioned using poster tubes (with the bottom sealed up) to make nice sized round soaps. As we’ve not had any posters or the like delivered recently, we haven’t got any of those but it got me thinking about similar cylinders: a litre-ish, straight-ish juice or pop bottles would probably about the right size, although it’d probably be awkward to get out like the olive oil bottle. That led me down another juice line: John has got a bit of an obsession with chocolate soya milk at the moment which comes in tetrapak containers – that would be a nice size for square bar soaps and be easier to cut out…

Anyway, long story slightly shorter, what else can I reuse or recycle to make either interesting shaped soaps or simple practical ones? If you make your own (cold-process) soap, what do you use?

Do you have any upcycled moulds that you can reuse again and again rather than destroying (like would happen with the poster tube or my juice containers)?

Or on the flipside, anything you’ve used that you’d urge other people not to use?

(A few notes for non-soap makers: the soap mix at the point of pouring is about body temperature for “cold-process” soaps so plastic melting is not usually an issue, but it is incredibly caustic at this point, and will react to metals other than stainless steel. It’s poured into the mould when it’s hit “trace”, a gloopy rather than full liquid stage, and left to set in the moulds for a few days, then popped out of the moulds to continue “curing” for a few weeks before use.)