can buy a USB adapter with a power source use outside a tower
not making a selling pitch this is what I use, under the DVD writer I use bottle top as legs using a glue gun work nice, use glue gun make them solid with the body like using super glue hold them in place!
btw add a drop of glue gun melted plastic to the top of the bottle caps, stop them from sliding around on you
use any brand you like, me I have USB (blue) v3.0 with that USB adapter above
this goes for any internal Hard drive too, electrical broad should be safe so double-check the units before trying this!