This bed leveling and first-layer calibration model uses a series of concentric squares with rounded corners to evaluate bed leveling, Z-offset, and first-layer consistency across a large portion of the print surface.

Unlike traditional corner test patterns, this design creates a continuous path that progresses from the outside toward the center and then returns from the center back to the outside. This helps reveal inconsistencies in bed level, extrusion, flow rate, and motion performance while minimizing unnecessary travel moves.

Features
Concentric square pattern with rounded corners
Continuous print path
Outside-to-center then center-to-outside toolpath
Covers nearly the entire printable area
Fits within a 200 mm × 200 mm envelope when printed with a brim
Fast print time
Minimal filament usage
Easy visual inspection of first-layer quality
Print Specifications
Nozzle Diameter: 0.4 mm
Layer Height: 0.20 mm
Total Layers: 4
Model Height: 0.80 mm
Recommended Print Speed: 20–50 mm/s
Infill: Not Required
Supports: None
What to Look For

A properly calibrated printer should produce:

Consistent line width
Smooth line adhesion
Uniform spacing between paths
No gaps between extrusions
No nozzle dragging
No excessive squish or elephant footing

If some areas appear thinner, wider, rougher, or fail to adhere properly, adjust bed leveling and/or Z-offset and repeat the test.

This model is intended as a quick diagnostic tool for verifying bed tramming, first-layer quality, and overall build surface consistency.