Soft rubber castors for chairs can be purchased at retail stores such as Home Depot, Home Hardware and Lowe's. U-Line has an assortment which may be suitable as well.
There are many places where one can buy casters and cart wheels online. This includes sites such as 'Castors Online', 'Ross Castors' and 'Wheel and Caster'.
You can find the best rates for casters if buying in bulk online. One such site is http://www.acecasters.com/products/specialofthemonth.html.
There are a variety of Casters wheels that work on ottomans. One should instead look at the material that the ottoman is being rolled over. Metal or sharper wheels may scratch hardwood floors, while rubber may scuff tile.
There are many retailers one could buy a good pair of soft shoes from. Amazon have a large range of soft shoes and one could also buy from John Lewis, Debenhams and Soft Spots who all sell soft shoes.
They wouldn't make a skillet out of soft (or any) plastic because it would only melt and burn. There are special silicone rubber skillets available, but I have not seen them myself and have no idea where to get one (check any e-commerce site).
You can find rubber tracks at many websites online. One website you can go to buy rubber tracks is http://www.mclarenusa.com/.
One can indeed buy personal playground equipment through Soft Play. One can also purchase playground equipment through Soft Play distributors in their home state.
One can purchase chair casters from various websites like Amazon or eBay. One could also visit a local furniture store and ask if they have any for sale.
One can replace office chair casters by searching online for businesses that either offer replacement so that one can do it at home, or for a business that will complete the service themselves.
I have had good luck finding soft top parts @ suzkicarparts.com.
you don't -Buy a new one
Your best option would be to contact the manufacturer. If you cant do this then you must visit the local hardware store with one of your current casters.