here's the sheldon brown ghetto version using a large nut/bolt and some large washers
probably available down the local hardware shop for not alot of pennies
+1 on this one...
Had the same issue with my niece's bike the other day - her BB was noisy and on stripping I found the bearings were shot - a quick trip to my parts bin found a suitable replacement (UN54 Shimano unit that'll probably outlast the BSO itself!).
Getting the fixed cup out was a faff to say the least, after struggling with spanners, mole grips and heat I dug around in my van and found a suitable nut & bolt and it came out easily - as you tighten the nut it should break the threads loose on the fixed cup as (assuming a "normal" BB) it'll be a left-hand thread.
My method didn't use the stack of washers though as not only was the BB was knackered anyway, the nut/bolt were from my scrap bin.
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Just a y2k FSR with some modern bits