Getting sore arms from holding that heavy hedge trimmer?

Well ... this design might alleviate the strain a bit :-)

The idea is to put your heavy battery in your backpack and only insert a lightweight adapter in your trimmer (or other Ryobi gear) to get the weight down.

I made af remix of the bottom of https://www.thingiverse.com/thing:1677812 for the adapter insert into the Ryobi - The top part is not modified - so use the top part from the link.

I used https://www.thingiverse.com/thing:1194867 for the battery clip but cut some slits (post print) to fit the nickel wire bands I've used.

For the connection between adapter and clip I used a standard (thick) 220V wire.
In order to get the curly/springy effect of the wire I wrapped it around a metal pipe and used a gas burner to heat it up. See more about the principle here: https://www.instructables.com/id/Make-Coiled-Wire/

The original motivation for this design is my plan to create a custom battery from an existing Ryobi battery with much more capacity - But in order to make this feasible I have to put the battery elsewhere or it will get too heavy :-)

A little snag -after prolonged use the electrical contact points gets hot, melting the PLA plastic in the vicinity - So I'm now trying out Polycarbonate to see if it holds up (surprisingly easy to print I might add).

Furthermore the wire should have leads with sizes at least 2.5 mm²

Note 2:
Great success! The polycarbonate versions are working splendid. I also replaced the original wire with some loudspeaker cable with leads of 2.5 mm² which I'm sure also contributes to the good result. With my new custom battery I was able to trim the hedge and still having more than half capacity left.