[Mirror Lake's BB]

I have seen the "California patch" method done in ceilings where old high hat light holes were patched. I don't know if I would do it in a wall where it might get bumped (I just don't know the strength). If you do use this method as recommended by jmen24, it should be noted that Durabond 90 is a setting type joint compound and hardens by chemical reaction and not by drying like your typical joint compound sold in buckets (I think quart size the smallest). The older/original Durabond 90 really can't be sanded and hardens like a rock. If you are a novice and use the original formulation, it may be trouble since you can't sand smooth. Also, the Durabond joint compounds are sold in powder form and you will be stuck with quite a bit.

If I had to do it in my home, I would first square up the hole. I would then cut strips of 1/2 inch thick plywood (since I have plenty around) probably about 2-1/2 inches wide and put pieces of this around the backside perimeter of the hole (half of the width exposed, the other half behind the drywall; hold in place and fasten with 1-1/4 inch drywall screws). Now cut a piece of drywall the size of your squared up hole, fit into hole and fasten to the already secured plywood pieces. I would use plywood since it won't split and I always have some around. Now finish like any typical drywall seam.

I have used the sanding type Durabond 45 for a first coat if I'm in a rush to apply the second coat. The numbers are either the working time in minutes or the hardening time in minutes.

This may be overkill for such a small hole but it works. If the hole is small, you could make the plywood cover the whole hole and extend maybe 2 inches on two ends.

Hope the above is clear enough. Again, just my two cents again.