Capping off bulkhead hole

[intarsiabox]

I got a free scrap piece of 1/4" acrylic, cut it to size and siliconed it over a hole on the back of my tank. I went with acrylic instead of glass because it is simple to cut to size yourself. If the hole is at the bottom of an overflow I would go with Vancouver Reefer and use a bulkhead and plug because unless there is enough room to slip a blade in afterward it won't be coming off again easily.