I recently purchased a set of Fotodiox Step Up Rings through Amazon (USA) for $13.95 USD. I purchased the kit in order to use a 58mm BW Polarizer I had already had on my Nikon 50mm F1.8D (52mm thread) and Tokina 100mm F2.8 Macro (55mm thread) as this was a cheaper alternative than buying a new filter.
The long time photo hobbyist and pros here will obviously already know about step up rings but figured it may be worth mentioning them for the newer hobbyist.
So here they are, the kit consist of 7 step up rings in the following increments:
49mm to 52mm
52mm to 55mm
58mm to 62mm
62mm to 67mm
67mm to 72mm
72mm to 77mm
As far as construction the rings are made out of aluminum (I think) and are the same quality as the metal rings found on low to mid range filters. Since by their nature the rings are designed to be thin and circular I'm sure you could bend if you're careless. However, after they are mounted to a filter and lens it shouldn't be a concern. Brass would be a better alternative but that would be unrealistic at this price range. Hey at least their made of plastic.
As for storage, you can easily fit them into a 1 or 2 plastic case that filters come in if you have on to spare. Their also quite sturdy when connected end to end and that provides another option for storage.
And here's the 58mm B+W Polarizer mounted to my 50mm F1.8D using the 52-55 and 55-58.
Vignetting may be a concern for some but unfortunate that's not a question I can answer for everyone. All I can say is it doesn't effect the 50mm F1.8D but I'm using a crop sensor camera with a full frame lens.