Remember that STL has no unit metadata
STL coordinates are just numbers. Maker workflows commonly interpret them as millimeters, but a model exported in inches can appear 25.4 times too small or large if the consuming software assumes millimeters.
Check dimensions before slicing
Model bounds quickly reveal unit mistakes and whether the object will fit the printer's build volume.
Inspect the actual solid model from every side
Drag the 3D view to orbit 360 degrees, zoom/pan, or use Front, Back, Left, Right, Top, Bottom, and Isometric presets. Feature edges, wireframe, X-ray, grid/axes, screenshot/fullscreen, distance measurement, and X/Y/Z section planes help inspect geometry that a flat screenshot can hide.
For raised text and logos, judge readability from the intended Front (+Z) face. The same artwork naturally looks mirrored when viewed from behind the plate; that does not mean the STL itself is wrong.
Triangle count affects handling, not quality by itself
Extremely dense meshes can slow browsers and slicers without improving a print. Very coarse meshes can visibly facet curves. OpenFileTools renders the exact parsed mesh and rejects files above its explicit triangle safety cap rather than silently sampling away geometry.
Volume assumes a closed mesh
A triangle volume estimate is only trustworthy when geometry is closed and consistently oriented. The viewer now reports boundary edges, non-manifold edges, orientation mismatches, and degenerate triangles so you can decide whether the volume deserves confidence.