Pellet gun / air rifle range target wizzer

The whizzer is just a box for a very simple reversible switched motor with speed control.  It does require some soldering, but it is very basic.  It is used to move paper targets up a range.

The whizzer uses a motor (about £3)

https://www.ebay.co.uk/itm/253823302357

Wired to a switched “DC Motor Speed Controller PWM Adjustable Reversible” on ebay (seem to all be the same, about £3 plus shipping from china)

https://www.ebay.co.uk/itm/192305624772.

2.1mm panel mount kit :

https://www.amazon.co.uk/gp/product/B07QNWSKN2

The two uprights fit on the gantry (and may need gluing), the gantry runs on two strings.  There is a loop of string that attaches to the center of the gantry and loops to your whizzer box.  There are two piece guides, they're printed like this so that they slot together and can be glued.  I wouldn't use the 3D printed pulley unless you have to, but they're expensive to buy, so printing may work.  

I have rounded the uprights so kids don't ping pellets off it too easily, they print flat on the build plate with minimal supports.  It's the same upright for both sides.  I did think of putting a small metal inset into the gantry feeds to prevent wear, but that's your call.  These aren't expensive to print replacements and I suspect they're going to find themselves as a consumable.

You'll also need a power supply and a 2.1 or 2.5mm sockets to plug the power into.  I used 2.1mm in this design, both should fit though with a bit of sanding.

Use black marker to highlight the letters on the top of the box and make sure when you solder up, the pulley goes in the right direction.

There are screw holes in the box which are used to mount it to a piece of wood to keep it anchored on the table.  You can use zipties to secure the motor so it doesn't spin.