There are a few other cable relief options out there for the heat bed but it seems they are a pain to attach, are way over designed or you have to have the bed removed. No thanks.
Remixed a cool bed handle I found, used it to make the cable relief. There is a Left and a Right version, depends on which side you want your cable to go.
It should just pop right into the slot. I would thread the zip tie through the notches before putting it on the bed.
This is designed for Wanhao/Monoprice Maker Select v2.1s, with the stock bed with the square notches and a curved raised lip. It wont fit on anything else most likely.
Lay it flat on the print bed and you are good to go. Use a higher infill over 10%, you don't want it sagging.