This add-in allows you to edit button images.

To install the add-in use the Tools > Add-ins menu and then browse for the ButtonEditor.xla file. This will add a new menu item to the Tools menu.

Once the editor is open you can use the tools (pencil, line, oval, rectangle, floodfill) to draw an image.

You can also load a 16x16 pixel bitmap direct from file.

Or you can copy an existing button. For users of XL2000 and later this can be done whilst the editor is open. For XL97 you should copy the image prior to opening the editor. 

To copy an existing button image you can use the built-in 'Copy Button Image'.  Right-click on any toolbar and a popup menu, similar to this one, will be displayed.
You can now right-click on the required button image.  This example illustrates copying the Merge and Center button image. You can now use the Paste button on the editor to load the image ready for editing. Once edited you can reverse the procedure using the Copy button on the editor and the 'Paste Button Image' on the menu.