For the bigger cones I use a metal stand that sets behind the machine, (just from my opinion I tried a plastic one and it was money wasted..it might work if you fill the base with cement or plaster). For smaller spools that don't fit my holder I have purchased, at a fabric store a wooden adapter that works really well, though their are some spools of thread that are smaller than even the adapter works for, so in that case I use a straw and it works wonderfully.
wooden adapter
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wooden adapter on spool of thread..$2 for a package of 2
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