This is a cap designed for use with the Profile 20x40 I-Type slot 5 from Motedis.
The link to the dimensions of the extrusion is shown below to allow you to assess whether this design would be likely to fit your 20x40 aluminium extrusions.
Printed at 0.2mm layer heights. 4 solid layers top and bottom for the base shape of the part. 30% rectilinear infill in between with the pins on top printed at 100% infill.