Zymic

Start a new document any size. Fill the bg in with a dark grey background. Then make a new layer and select the polygonal lasso tool and make a selection similar to below:

Fill the selection in with white and press [Ctrl + D] to deselect. Open up the layers blending options and select [Gradient Overlay] and use the settings below:

Now select stroke:

It should now look like below:

Make a new layer underneath layer 1 and grab the polygonal lasso tool again, make a selection like below and fill with white. Then press [Ctrl+D] to deselect.

Bring up the blending options for the current layer and select [Color Overlay]:

Inner Shadow:

Stroke:

Select the [Move] tool and tap [Arrow Up] on your keyboard, untill it looks in the same place as below:

Now grab the [Eraser] tool, select [block] in the mode option at the top of the screen and zoom in as far as you can. Erase the outer corners pixel as show below:

Once you have done all the outer corners your button should be looking like below:

Now we need to add some text, I chose a small pixel font and completed my button as shown below:

Simply duplicate the layers like I have below and you should be finished!