Battery adapter 9V to 4.5V

thingiverse

This is an adapter to use/substitute a 9 volt batter in a 4.5 volt site. To easily remove the 9volt battery from the adapter, I use to add a tape attached to the back of the battery. It could be necessary to make some modification post-print. to create the contacts I used rolled and flattened tinfoil but if you can use something better