Provided here is a set of parameters (and their associated macros) that will allow you to create a parametrically controlled Lego compatible brick design that can be easily 3D printed.  And it even meshes well with the real Lego bricks.

Lego has an interesting set of design parameters that have all been incorporated into these macros.  There are only a couple of “fudge” values that make the design work well with FDM printing.

You should find in the pictures section an image of the basic design and the parameters that drive that design. Also included is a CSV (comma separated values) file that contains all of the macros.

Key User Parameters

There are four key user parameters (I suggest marking them as “favorites” in your macro editor):

• LENGTH - this is the number of studs in the “y” direction.
• WIDTH - the number of studs in the “x” direction.
• HEIGHT - the number of “special” Lego units in height.  It should be noted that a height of “1” is the equivalent of a Lego-plate and a height of “3” is the height of a normal Lego brick.  Hey, this is Lego stuff not my own.
• SCALE - a value that allows you to scale the Lego brick to be almost any size.

It is worth noting that the parameter “ClearanceOutside” (0.2 mm) takes the place of the normal Lego brick clearance (0.1 mm).  Anytime you see ClearanceOutside it represents the FDM compatible spacing.  Anytime you see the Tweak parameter it is used to match the “actual” Lego dimensions (differing from the published rules).  There are a few times that you will see FUDGE, which is used to allow for better compatibility with FDM printing.

Model Creation

I will be adding instructions for creating a 3D model.

[TBA]

Printing

No supports should be needed when you are printing at normal scales.

All prints are done using a 0.4mm nozzle and 0.2mm layer height.

Some History (If you are interested)

I have been working on a marble run that can integrate with Lego bricks for one of my grandchildren's school projects.

[TBA]