Basically as the title says, I needed to get some power to my new Ryobi 18v drop saw that I had bought. I wasn't likely to go out and buy a rack of chargers and batteries for Ryobi when I have a heap for my DeWalt tools already.

I made an adaptor to save me a heap of money.

Step 1: How and What

Ingredients:

32mm heavy duty conduit
90x45 pine
scraps of wire and some metal for a set of contacts
sacrificial DeWalt tool
superglue and screws, etc.

Method:

It's going to be easier to follow if you watch my video, I edited out most of the ummmms and arrrghs.

Basically though, deform the conduit using heat, (I have a video or instructable on a DIY hot box somewhere.) so it fits in the base of the tool.
Trim the conduit so it has somewhere to seat some contacts which you will need to form up out of something metallic
Work out the polarity of the dummy battery you are making and solder some wires to the contacts and feed through some holes you should drill in the conduit.
Cut the base off your sacrificial DeWalt tool and clean out the connector for the battery of anything that may cause a fault condition due to it conducting.
Screw both the conduit into a hole in your pine and also the base from the tool to the pine.
Connect the tails of your wires to the DeWalt tool base.
Insert into your Ryobi tool, add a battery and you are good to go, you may need to come up with something to keep the adaptor in the tool but your options for this will be dictated by the tool you are using.

Thanks for having a look at my instructable!