FWIW gun manufacturers are immune from civil suit when some whack job goes on a killing spree. However accessory manufacturers are not immune and my guess is that there will be at least 600 lawsuits filed against the bump stock manufacturer who made Paddock’s bump stocks.
You won’t have to regulate them because nobody is going to make them.
They’re also sort of self-regulating in that they tend to ruin many tifles that use them