This one is from Amazon, I think for what you would be using for here, it should be sufficient. 60 lbs breakaway force should hold fairly well and it appears rather small in size too. Can't beat the price either.
Only concern I see with this one is the size of the switch knob and if it would get in the way while working with it. Need to find some other pictures of it.
Found a picture to give relative size of item. The knob could get in the way. But I think if you could build a holder for it out of a piece of wood or aluminum, to move the knob away from the work, you may be able to use it. If you milled a slot the width of the flat side of the Magswitch it may work.