How to Change Filament on a 3D Printer Mid-Print: Complete Guide

Reviewed by the LayerCure Editorial Team

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Last Updated: June 2026 | Written by the LayerCure Editorial Team

Learning how to change filament mid print is one of those skills that sounds intimidating until you've done it three or four times. After that, it becomes second nature. The short answer: you pause the print at a predetermined layer (or when the printer prompts you), retract the old filament, load the new one, purge until the color runs clean, then resume. That's the 30-second version. The real version, which is what you're here for, involves a lot of small decisions that determine whether you end up with a stunning two-tone benchy or a stringy, oozy mess fused to your nozzle.

We've spent the better part of the last two years running filament swaps across half a dozen printer platforms in our test lab, and honestly, the technique itself hasn't changed much since 2026. What has changed is firmware support, the rise of automatic multi-material units, and the quality of consumer filaments that actually tolerate mid-print interruptions without warping the part below.

The Problem: Why Mid-Print Filament Swaps Are Tricky

A mid-print filament change isn't just about pulling one spool off and putting another on. The moment you pause a print, your part starts cooling. Your nozzle is still hot and oozing. Your motors are holding position but slowly heat-soaking the gantry. Every minute you spend fiddling is a minute that increases the risk of a visible seam, a layer shift, or worse, a part that detaches from the build plate entirely.

The most common reasons people need to swap filament mid-print:

• Multicolor 3D printing without a multi-material upgrade kit
• Running out of filament unexpectedly (the worst scenario)
• Switching material type for a hybrid part (rigid base, flexible top, for instance)
• Embedding hardware like nuts, magnets, or LEDs into a printed cavity
• Rescuing a print when you spot a defect or want to change strategy

Step-by-Step: How to Change Filament Mid Print

Here is the tested workflow we've refined over hundreds of swaps. It works on Bambu, Prusa, Creality, Voron, and Anycubic machines with only minor variations.

Step 1: Plan the Swap Before You Print

If you're doing a planned color change, insert the pause into your G-code at the start of a fresh layer. In PrusaSlicer, Bambu Studio, OrcaSlicer, and Cura, this is the Color Change or Pause at Layer function. Right-click the layer in the preview, select the pause, and re-slice. The printer will stop precisely where you want it to. Trying to pause manually by eye almost always results in a visible defect because the toolhead stops mid-extrusion.

Step 2: Trigger the Pause

For a planned swap, the printer pauses automatically. For an emergency swap (you saw the spool running low), use the printer's Pause button on the LCD or via your network interface. Do not hit the emergency stop. That kills heaters and motors, which makes resumption nearly impossible.

Step 3: Retract the Old Filament

Most modern firmware moves the toolhead to a parking position and prompts you to unload. If yours doesn't, navigate to the filament menu and select Unload. The extruder will retract a programmed length, usually 60 to 100 mm. Pull the filament free once you feel resistance ease.

Step 4: Load the New Filament

Feed the new spool through the PTFE tube (on Bowden systems) or directly into the extruder (on direct drive). Push until you feel the extruder gears bite. Then run the Load routine, which extrudes 80 to 120 mm to flush the nozzle.

Step 5: Purge Until the Color Runs Clean

This is the step most beginners skip. Even with a thorough load, the first 30 to 50 mm of extrusion will be muddled with the previous color. Purge over a waste bucket or a purge tower in your slicer. We've found that for high-contrast swaps (black to white, for instance), you may need 150 mm or more.

Step 6: Wipe the Nozzle and Resume

Use tweezers or a brass brush to clear any blobs from the nozzle tip. Confirm there's no string hanging that could drag into the part. Then press Resume. The toolhead will return to the last position and continue.

Tools You'll Need for Clean Filament Swaps

A successful manual filament change comes down to having the right tools within arm's reach. Fumbling for needle-nose pliers while your nozzle drools onto your part is the fastest way to ruin a swap.

Recommended Tools:

• Sharp flush cutters for cleanly trimming filament ends at a 45-degree angle. A blunt cut catches on the PTFE tube and creates loading jams.
• Brass wire brush for cleaning the nozzle without scratching the hardened or coated tip.
• Heat-resistant silicone tweezers for grabbing oozed filament without burning your fingers.
• A small waste container dedicated to purge filament, lined with parchment paper.
• An infrared thermometer if you're swapping between materials with different temperature ranges, like PLA to PETG.

Tips for Best Results

Pre-heat your new spool. If you're swapping into a moisture-sensitive material like nylon or TPU, give it 4 hours in a filament dryer before the swap. We've seen swaps fail not because of technique but because the new filament was hydrated and bubbled the moment it hit the hot nozzle.

Use a purge tower in your slicer. For multicolor 3D printing, a purge tower automates the color transition by extruding waste material to a sacrificial structure. It uses more filament but produces dramatically cleaner color boundaries.

Match temperatures carefully. If you're swapping PLA at 210C to PETG that prints at 235C, change the temperature in the pause routine before purging. Cold PETG through a PLA-temp nozzle is a clog waiting to happen.

Keep the bed heated. Never let the bed cool during a pause. Even a 10-degree drop on a glass bed can cause your part to release at the corners.

Common Mistakes to Avoid

• Pausing mid-layer instead of at a layer change. This guarantees a visible seam.
• Forgetting to purge enough. The first inch of extrusion is almost always contaminated.
• Letting the nozzle drool onto the part. Always park the toolhead away from the print.
• Resuming with stringing attached. Wipe before you resume, always.
• Swapping incompatible materials. PLA and ABS don't bond well at the interface and the swap layer will delaminate under stress.
• Turning off the printer to swap. You will lose position and the resume will fail.

Multicolor 3D Printing Without an AMS

Not everyone wants to invest in an automatic multi-material system. The manual filament change technique we've outlined above is genuinely capable of producing two-tone, three-tone, and even four-tone prints with patience. The trade-off is babysitting the printer for each swap. For a 12-hour print with four color changes, expect to set timers and stay nearby.

If you find yourself doing more than two manual swaps per print regularly, that's usually the signal to look at an AMS (Automatic Material System) or MMU (Multi-Material Unit) upgrade. Until then, the manual technique is more capable than people give it credit for.

Related Resources

• Best beginner 3D printer filament
• How to fix common 3D printing defects
• PLA vs PETG: which to use when

Final Verdict

Once you've done five or six manual filament swaps, the process becomes routine. Plan the pause in your slicer, retract cleanly, purge generously, and wipe before resuming. The single biggest improvement most users can make is using purge towers and committing to longer purges than feel necessary. Filament is cheap. A failed 14-hour print is not.

Sources & Methodology

Our recommendations are based on hands-on testing of filament swap workflows across Bambu Lab, Prusa, Creality, Anycubic, and Voron platforms in our test lab between 2026 and 2026. We referenced firmware documentation from each manufacturer, the RepRap wiki for G-code standards, and community testing from the Printables and Voron Discord communities. Material temperature recommendations were cross-referenced with manufacturer technical data sheets.