When you are in an awkward position trying to attach a nut to a bolt, a finger wrench may be just what you need. Tight corners especially, and anywhere that requires reaching into the unknown: dropping a spanner down the back of a radiator is all too easy, dropping your finger is not.  
I recently discovered this great little gadget on a DIY blog but unfortunately the company that originally supplied it is no longer making the product (why not??) and i can't find anywhere to purchase existing stock.  
I had to have one, so I modelled and 3D printed this little beauty and it works a treat!  
Easy to use:
There is a gap all down the back side, thereby allowing one size to fit a wide range of fingers. Slip a nut or bolt into the wrench as shown in the two images. Finger pressure keeps the nut or bolt in place. The tapered slot inside the wrench prevents the nut or bolt from turning.  
Suitable for 1/2inch nut/bolt and smaller.  
Print PLA (http://www.faberdashery.co.uk/products-page/print-materials/mellow-yellow/)…