A maker known as 'I changed a thing' has mounted two diode lasers to the X-axis of an FDM printer and used them to melt layer lines into smooth surfaces, producing results comparable to vapor smoothing without acetone, fumes, or explosion risk.
Top surfaces responded well to the technique. Walls are harder: the laser must hit obliquely, and optimal results depend on object geometry and size. The builder tested both layer-by-layer melting during the print and post-print passes on finished objects. Neither method wins universally, which means replicating this requires experimentation, not just copying settings.
This builds on the same builder's earlier laser layer-adhesion work and follows a 2025 project that used non-planar toolpaths for post-print laser smoothing. The full videos show where the technique succeeds, where it fails, and exactly how the dual-laser rig is configured. That hardware detail alone is worth the watch.
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