given a choice between the SideWinder and pre-wounds, i would vote for pre-wounds.
they are available in cotton now, too.
i own three different bobbin winders.
the two "professional" models have a very steep learning curve.
none of them all as simple to use as in the demonstrations.
pre-wounds have obbledygoogobs of thread wound onto them compared to anything we can wind ourselves.
given the price of thread, plus the price of bobbins, they cost only a smidgen more than buying what we need to do it the hard way. probably not the best solution for special colors, but definitely very convenient for the basic colors we use for piecing.
this is where i start when shopping around for them.
i'm sure there are other good sources.
this just happens to be the one i use.
https://www.terradonembroidery.com/s...d_bobbins.html