Supermarket Trolley Self-Scanner Holder for Right-Handed People (or for left-handed on right-handed trolleys!)

UPDATED - V2 NOW AVAILABLE IN REMIXES. You'll still need nut/bolt info from this model but if you want the TPU bar clip version then get the STLs from the V2 remix.

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This is specifically designed for our local Sainsburys trolleys, but might fit others. The plastic coated crossbar on our trolleys is about 25mm diameter, and the centres of the plastic coated bar and the chrome crossbar are about 120mm apart.

Some utter numpty completely ignored the fact that 90% of people are right-handed when ordering their trolleys with the self-scan holster on the LEFT!

The device could equally be used by left-handed people in places where the supermarket has bought right-handed trolleys :o)

This has annoyed me for many years, as my left hand is great for holding things for my right hand to work on, but it's useless at pointing at things, eg with a scanner. So now I have a 3D printer, it's time to fix the problem :o)  I'm fed up with having to reach across to the left side of the trolley to grab the scanner, scan something, and then reach across again to park it in the holster.

This is a fairly early version which may need refining. But it's reached the stage where it can be used so I'm publishing it now.

I made it in two parts in case some of the trolleys are welded slightly differently with the chromed crossbar in a different position. The two parts are designed to be joined with an M3 non-countersunk-head bolt and a nut which fits into a matching recess - I used a hex-cylinder-head bolt because that's what I had in stock, and printed one of these excellent finger-tightening knobs and glued it to the bolt head to avoid having to take any tools to the shop for adjustments https://www.printables.com/model/751427-knurled-handle-for-cylinder-head-screw 

Drop the STLs into your slicer, they should be the right way up already for printing, no supports or adhesion needed. I used 0.2mm layers and 0.4mm nozzle, you can increase infill for a bit of extra strength if you like but as this was a prototype I just used standard 15% infill and it seemed strong enough until one of the curved arms that grab the trolley handle snapped so now I use 35% lines infill and 4 walls :o)

I neglected to realise the main bar clip had an overhang which didn't print perfectly so I've corrected that for the STL published here, as well as filleting the end hook to make it look rounder. 

If you don't want to use a nut and bolt, you could just glue the parts together once you've tried it on a few trolleys and marked what position to glue it in. 

I printed with Elegoo PLA+ filament - pretty much any material ought to do the job.  

I was really pleased when I tried it out in the shop, you can either hold an item in front of the scanner and prod the button, ideal for small items, or lift out the scanner and scan and then drop it back in. Works perfectly! Future enhancements might include angling it upward slightly more, and possibly thickening up the connecting bars.

I hope this is handy for someone else too! Please post your makes and comments. If you really like it there's also https://www.buymeacoffee.com/gigabeast :o) :o)