A VESA-to-pegboard adapter has two jobs at once: bolt to the back of a monitor or device using a hole pattern you did not choose, then hang securely off a pegboard using a different spacing you also did not choose. Get either pattern wrong and the part is scrap, not adjustable, because screw holes that miss by a few millimeters do not "mostly work."
This post covers the two real VESA patterns, why the screw hole is sized the way it is, and the print orientation that keeps the pegboard hooks from being the first thing that breaks.
VESA 75x75 and 100x100 are M4, not a guess
VESA's official mounting spec for monitors and small displays, MIS-D, defines two square hole patterns: 75mm x 75mm and 100mm x 100mm, both using M4 screws. If your device is under about 14kg, one of those two patterns is almost certainly what is on the back of it; larger displays step up to 200mm and beyond, which is why Meshra's VESA connector accepts any pattern from 50mm to 200mm rather than hard-coding just the two common ones.
The VESA spec also calls for each mounting hole to be 5mm in diameter, not 4mm to match the M4 screw exactly. That extra half a millimeter per side is deliberate clearance built into the standard itself, so the screw has room to seat even if the four holes are not positioned with zero error. Meshra's VESA-to-pegboard connector defaults its screw hole to that same 5mm, and exposes it as an adjustable 3 to 8mm parameter in case your hardware kit uses something else.
The pegboard side: pitch, not a pattern
Where VESA is a fixed international standard, the pegboard side is not: hole spacing varies by manufacturer and material. The most common spacing on standard pegboard sold in the US is 1 inch, 25.4mm, which is why it is Meshra's default and first preset; 25mm (the metric equivalent used on some boards) and 1/2 inch, 12.7mm, on finer pegboard, are the other two presets. Measure your actual board with calipers before you derive the part, the same way you would for any mounting target: a tape measure across several holes and dividing will not catch the difference between 25mm and 25.4mm, and that 0.4mm error compounds across every hook on a wide plate.
Once you have both patterns measured, the connector's fit slider adds the same clearance math used across every Fit Machine connector to the pegboard side: the hook's opening is sized to your measured board thickness plus a snug, normal, or loose radial clearance, so the same plate seats on a 4mm hardboard pegboard or a 6mm plywood one without redesigning anything. Our post on 3D printing tolerances covers why that clearance number matters more than the nominal thickness printed on the box.
Print orientation: flat, screw face down
By default, a VESA-to-pegboard plate at a 100mm pattern comes out around 120mm square and only about 5mm thick, with two small hook pegs (roughly 6mm square, under 10mm long) sticking off the back. That size difference decides the orientation question for you: printing the plate on edge means balancing a 5mm-thin wall over a 100mm-plus span, which needs a forest of support and rarely survives the print. Printed flat instead, with the screw-hole face down on the bed, the wide, thin plate gets full bed contact and prints fast and flat, and the two pegs and their barbs point straight up into open air where the only real overhang is the barb itself, a short horizontal shelf near the top of each peg. Most slicers bridge that cleanly at default settings; add supports under it specifically if yours is conservative about overhangs.
That orientation is also where the part is most likely to fail under real load if you skip one detail. Every gram of the mounted device pulls down through the peg where it joins the back of the plate, and printed flat, that junction sits right on a layer line, the weakest plane in any FDM part. It is the single most common failure point on printed pegboard hooks generally, not specific to this connector, and the fix costs nothing: bump the perimeter (wall loop) count and infill percentage in your slicer, or apply a stronger profile specifically in that region if your slicer supports per-feature settings, rather than printing the whole plate at a thin default.
Where to start
Open the VESA-to-pegboard page in the Fit Machine, enter your VESA pattern and pegboard measurements, and pick a fit level. The result is a real, editable plate with both hole patterns and the clearance already built in, deterministic and free on every plan, no AI call. It lands in the builder afterward with a full parameter drawer, so if a screw is a different size than the default or the hook still needs a touch more clearance after a test fit, that is a slider away, not a redesign.