here is my simple custom plate holder for the Wanhao Duplicator 7.
The buildplate is approx. 75mm by 134mm in size. Just print two of the custom holder, screw them (holes are for M3 screws) or glue them on. You will also need four M4 nuts for the stock screws Wanhao is using. Other than that the thing works exactly the same as the mount of the original plate.