Porter Anthony

I fix appliances and replace the rollers on clothes dryers quite often. Usually there are 4 to 6 rollers and when I change them all out half of them are still good (but since I have the dryer taken apart, the customer usually wants them all replaced considering the labor cost)
Anyhow, the rollers are about 3” in diameter with a 1/2” bore hole. They are held in place by a post a few inches long. Whatever cart I make would have to have post axles instead of one axle through the whole thing. If I could figure out how to turn them into casters I would but I think they will have to be attached to the side of whatever I make.  I like to put casters under everything so it’s never hard to move things around. Im trying to come up with ideas that would make something useful or better not necessarily a toy or something like roller blades. I.E. a heavy duty drawer roller, air compressor wheels, etc.
ps I work with 8 other techs so Ive been saving a few rollers & have unlimited supply.

Any ideas?

I am trying to make an off-grid water system for a small cabin and I am trying to put together a small water system similar in design as one that would work in a trailer or RV.  
This will be for using small amounts of water for flushing toilet/short shower/front load washing machine that uses very little water/ dishwasher that uses very little water
Here are my parameters:
WATER SOURCE: four 55-gallon barrels of reverse osmosis reject water (I am going to connect these in series so they act as one 220 gallon cistern.
PUMP: (I know most would probly say that this is not the right pump to use, but is there any janky way to jerry rig this to work?):
Option #1: Small diaphragm pump – 12V DC freshwater pump with pressure switch 1.2 GPM 110PSI (6.88 Bar) Cut off pressure.  Adjustable for RV, Camper, Marine, Boat, Lawn.
Option #2: Sump Pump?  I have several on hand but could not find out if you could use one for a pressurized system.
Pressure Switch: The pump has a pressure switch at 80-100psi.  I have a SqureD pressure switch rated at 30-50 psi.  Can I hook up this pressure switch to the pump and will this bypass the pressure switch built into the pump?
Pressure relief valve: I need to get one for my system. Is this mandatory?
Pressure tank: 3.5 gallon RO pressure tank that I think is pressurized at 6-10psi when empty; 30-40psi when full.  Ideally, I will get a larger tank but could this work in a pinch for a small system?
Delivery system: ½ inch PVC line about 25 feet to end point with only four 90 degree elbows to sink faucet.

Any advice is appreciated!!!