3D Printed Custom Molded Holster

I wanted to make a custom molded hard shell holster for my 31K-H311 nerf gun, and thought that making it similar to how real kydex or leather holsters are made would actually be really easy.

Hardware required:

• Lighter/heat gun/blow dryer (something that can get plastic hot enough to soften it)
• Some size of 6-8mm long bolt and nut (I used M5)
• Gloves to handle the hot plastic without burning yourself

Current templates:

• 31K style nerf pistols
• YEHW style nerf pistols
• TheTrigger nerf pistol
• Ehdrien Knockout mod nerf pistols
• Hecate Bigshock mod nerf pistols
• MHP's Magpie Mk2 nerf revolver

I AM NOT RESPONSIBLE IF YOU HURT YOURSELF WHILE DOING THIS. SAFETY FIRST.

PLEASE USE THIS FOR TOY/PROP GUNS ONLY.

Here's the process I followed. In total (with printing) it took less than 2 hours to go from sketching to final piece.

If you want to skip the customization process and just learn how to do this for a pistol shape covered in the files, skip to step 3, or watch this video:

Step 1: Template layout

Grab a sheet of paper of the appropriate size, I used tracing paper because it makes the whole process way easier, but regular paper will work as well.

Start by folding it over the gun, and drawing the outline of the holster. Reference some real holsters for the final shape you want. (Ignore the scribbled out section, my first draft was too long).

Do this on both sides.

The side you want against your hip should have the taller tab, but this can be changed later in the digital design stage.

When you are done you should have a continuous design on your sheet of paper.

Take a well lit picture of it, this will aid in the digital conversion. Do your best to take the photo from directly above to avoid distorting the dimensions.

Step 2: Digital design

Take that nice clean image you took, and import it into your editor of choice. You could go straight into 3D modeling, but I decided to import it into a vector program and create the shape there first. My program of choice was Inkscape (free).

Do your best to follow the proportions of the shape you drew, and clean up the outline to be smooth, and make the ends as close to symmetrical as you can.

From here, we import it into a 3D program, here I chose Blender (free) because it is what I'm familiar with.

It will need to be re-scaled to match the dimensions of the original drawing, so measure the drawing and adjust appropriately.

Convert it to a mesh, and extrude to 2mm thick.

Here you can also make any other adjustments you want. I chose to add in some belt slots.

After this, it can be imported into your slicer and oriented for printing. Print at 100% infill, whatever walls. I used a smooth PEI plate, the plate will need to be heated to 100c, so I don't recommend a cool plate. I'll cover this again in step 4.

Step 3: Gun model prep

For a successful mold, your gun will need some bits added to ensure it can be safely molded and has all the bits needed for it to be drawn and holstered smoothly.

Start by looking for any parts that stick out past the regular frame, for example:

Here I'm not too concerned with the safety, since its a small bump and likely won't cause issue, but the front iron sight will be a problem if we don't account for it.

I made a small rod from some tape and paper, and a small cone that sits where the holster ends.

Now when we mold the plastic, the front sight will have room to slide in and out.

Step 4: Printing and molding

Print settings are pretty simple, 100% infill, any number of walls, and a hot plate of some kind (or any plate that will handle high temps and still let you pull the plastic off the plate).

I printed my holster out of PLA, but PETG or other filaments with lower softening temperatures should be suitable.

Immediately once your print is done and BEFORE IT HAS A CHANCE TO COOL, set the print bet temp to 100c. This will both make the plastic soft and give you ample time to mold the sheet once removed from the bed.

Ensure you have your prepared gun model on hand, and are wearing some heat protective gloves.

You can watch this short video on how to form the holster once it's ready. Really focus on the trigger area, as that is what the gun will rest on when in the holster.

Step 5: Post-processing

Now that the main shape is done, you can fasten it together and use your lighter or heat gun to work in the fine details. 

Drill a hole into the plastic under or next to the trigger guard bulge, and screw in your choice of bolt + nut.

The first thing I did after that was bend out and splay the belt loop.

Finally I flared the top lip out so the gun could be inserted more easily.

And thats it! You're done!

Hopefully your holster came out great.