DesignFind

With this design you can use regular AA batteries for devices using C batteries. 

As Christmas coming along a lot of toys we got for our kid require C batteries and not having a pile of those chunky  batteries laying around I though I can make an adapter. 
As far as I know the aa battery has the same output as C battery except for capacity (meaning the battery dies faster) which in my case using rechargeable batteries I can care less. 

The idea is to make some spacers around the battery to be able to hold the AA battery in place and use it as a D size battery. the same should be possible for D size batteries with some small tweaks on the outer radius of the spacers. 

In this project I used 1/16 inch thick basswood sheets and that's important since we are working with some joints here but do not worry as you can edit the file to whatever size your material is by measuring your material thickness and using it for the width of the yellow group shapes.