Half Life Alyx Healing Syringe / Health Pen - with electronics

This is the healing syringe from Half-Life: Alyx. These can be used by the player and can often be found on the belts of Grunt Combine soldiers

This model has a space to have LEDs that light up the liquid inside the vial like in the game. You can also not add the electronics and it will work too.

The electronics are 4x 3mm green LEDs. They are powered by a small 3V lithium battery that's the size of an AA battery but half its length. The cables go through the channels in the "glass.stl" file and up to the hole inside the "big red part.stl" where the battery and a tiny switch are located. The "big red part.stl" has space for two 5x5mm cylinder magnets which attach to another two magnets of the same size in the "knob.stl" file.

For a more seamless connection the upper white part of the syringe slides in at where there's something that looks like a hinge connecting it to the lower white part that also has the + symbol.

The + symbol's size irl is 8mm x 33mm. 8 is the width of the "arm" and the 33mm is the full length across.

I added 2 screws that I melted into the plastic with a soldering iron, those screws are 2x flat head m6 screws with a 10mm head, the head size is more important here.

For the needle, it is 0.8mm thick and sticks out 19mm from the base. You can buy these needles in drugstores, they're dirt cheap.

For the tips that hold the needle I made 2 versions that can be swapped. If you don't need that you can just glue it in place. If you want to have it replaceable then here's how I did this. I used some small nails I had lying around that I cut off the heads and glued them to the tips. In the tips there are these indents with a deeper and narrower indent in the middle. The one in the middle is for what will be left of the shaft and the bigger for the head. I put a magnet in the syringe so that the tip attaches to it. This also should be a 5x5mm cylinder magnet. I recommend putting something on the nail head so that it doesn't stick to the magnet as much, I put some fabric electric tape, without it it was really hard to get it out.

For the vial I used a plexi hollow tube with 25mm in diameter and 2mm wide wall - this will be needed so that some of the parts fit if you're going to be adding the electronics.

For the green liquid I had way more trouble than I thought. It's very hard to have a colored liquid that also is a bit cloudy and doesn't get bad with time from either it rotting or some part of it setting on the bottom after a while.

I found that for the most lasting effect I used a mix of fabric dyes that you dissolve in hot water, I mixed green and blue to get the right shade and gloss varnish acrylic paint for the cloudiness.

For a better but short lasting effect I also tried working with highlighter ink mixed with washing machine white liquid soap for the cloudiness. The washing machine soap is worse than the varnish though imo, it seems to clot up the paint. The highlighter ink seems to separate and get really blue if you mix blue, yellow and green inks. It's brighter when lit and more vibrant, but since the liquid is going to be glued shut, then the longer lasting one is better imo.
This should be all, ask me in comments about anything if you need help.