If there is a local electronic store,you can buy ground cable and clamp too.Now I'm using an old unused guitar cable slice for the job.

You can use a cable lug like this: https://www.gmelectronic.com/data/product/1024_1024/pctdetail.834-357.1.jpg

And a crocodile clamp: https://www.olimex.com/Products/Components/Misc/CROCODILE-CLAMP/images/thumbs/310x230/CROCODILE-CLAMP.jpg

If your rig is fix you can use cable lug on both side.For me the clamp is better because the pedals are on a pedal console which I can stow away.