This was a project at my own home. When I remodeled my kitchen it would have been almost impossible to move the switch on the wall closer to the sink. I didn't want to drill a hole in my new wood countertops for a surface switch so I had to get creative.
To turn on the disposal now I just have to move a magnet over a reed switch under the countertop.
This magnetic garbage disposal switch was made with less than $15 in parts.
1 x 115VAC SPDT Power Relay 16A 380VAC (271-1009) = $3.00
1 x Large Reed Switch-Normally Open (280-1007) = $0.75
6 ft. 14/3 SPT-3 Wire Air Conditioner/Major Appliance Extension Cord with Right U-Ground Plug, Gray $6.79
1-Gang 22 cu. in. Heavy PVC New Work Electrical Outlet Box - Blue $0.87
1-Gang Blank Handy Box Cover = $0.64