How to Make Your Own PCAR

Update: 22/07/2026: Updated Model. 

How to Make Your Own PCAR

Please see my other upload "Swappable PCARs for Foam Dart Springer Blasters" to understand what this is. 

Cheers

Using the Fusion 360 file + PCAR Twist Calculator

This walks you through customising the PCAR to fit your barrel and dialling in your own twist rate, then exporting an STL ready to print. It looks long, but it's mostly a few dimension changes and one twist-angle number. Take your time the first time and it'll be quick after that.

Step 1.  Download the files

From the Printables listing, grab both:

●      The Fusion 360 file  (“PCAR Choose your own” – or whatever I've named it on the listing)

●      The PCAR Twist Calculator spreadsheet

Step 2.  Get Fusion 360 (if you don't have it)

Fusion 360 is free for hobby use under Autodesk's personal / hobby licence. Download it from the Autodesk site, install, and sign in.

Step 3.  Open the file and find the sketches

Open the Fusion file. On the left in the browser, expand Bodies and Sketches (click the little arrow beside each). Every sketch is labelled either “DO NOT TOUCH” or “EDIT ME” – you'll only ever change the EDIT ME ones.

Tip: If a sketch is hard to select because the PCAR body is in the way, expand Bodies and click the eye icon to hide the body while you edit, then turn it back on afterwards.

Step 4.  Set the collet fit (first EDIT ME sketch)

This sets the inner diameter that sits on your barrel. Right-click the first EDIT ME sketch → Edit Sketch. You'll see the dimension I've entered (16.6 mm). Double-click that number and type your own value, somewhere between 16 and 17 mm, then click Finish Sketch.

The collet can be a little loose – it's the PCAR body itself that you want snug. Because my barrels have a coating on the outside I use 16.6 mm; bare barrels are often around 16.3–16.4 mm.

Tip: The collet is a small, quick print. Print just the collet first to test the fit on your barrel before committing to a full PCAR.

Step 5.  Set the PCAR body fit (next EDIT ME sketch)

This is the main body, and you usually want it a touch tighter than the collet. Right-click the sketch → Edit Sketch. It's set at 16.6 mm; double-click and change it to whatever suits you between 16 and 17 mm. Some people run 16.2–16.4 mm for a snugger grip. Click Finish Sketch.

Step 6.  Get your twist angle from the calculator

Open the PCAR Twist Calculator. In the yellow input cells, enter ONE value only – either your twist rate (1 turn in X mm) or a BCAR-equivalent angle. (If you fill in both, it'll show a warning.) The green cell then gives you the Twist angle over section length.

Write this number down – you'll need it in the next step. Example: I enter 575, and the green cell shows 50.09 degrees.

Step 7.  Apply the twist in Fusion

Look at the History Timeline along the bottom of the Fusion window. The fourth icon across the one that looks like a little square snake – hover over it and it's labelled with the Edit me: enter angle. Right-click it → Edit Feature.

The only thing to change here is the Twist Angle. Type in the number from the calculator (e.g. 50.09) and click OK. The model updates on screen. Hold the mouse wheel down and drag to rotate and check the rifling looks right.

Step 8.  Update the label (EDIT ME – REMEMBER TO LABEL)

Back under Sketches there's an EDIT ME sketch for the label, labelled Edit me: Remember to label. Right-click → Edit Sketch (hide the PCAR body first if it's blocking the view). Double-click the text and change it to your twist rate / name so you can tell your PCARs apart. Click OK, then Finish Sketch. Turn the body's visibility back on.

Your PCAR design is now finished.

Step 9.  Export the STL

In the browser, right-click your PCAR body → Save As Mesh. Click OK, give it a name, and use the three dots at the end of the location field to pick where to save it on your computer, then Save. You now have an STL ready to print.

Step 10.  Print it

Recommended print settings:

●      0.4 mm nozzle

●      0.2 mm layer height

●      4 walls

●      15–40% infill (your preference)

●      PLA or PETG – either is fine

That's it – as simple as that. Any questions or feedback, let me know.