Flush handle hole plug

Recently I installed a Vimtoba touch less toilet flush system, which works with the wave of your hand over the tank top. Unfortunately, you need to remove the original flush handle as not to be confusing for someone not familiar with the system, but the kit doesn't come with a plug to fill the hole so I designed one. The picture shows the plug in black, which I used to show up in the photo, but the actual plug is white. This is for a Kohler toilet with a .70 square hole. I don't know if this is standard, but it may work on other brands. I use PETG, but most any filament will work for this part.