8020 1530 bar

From the official website:

1530 is a 1.50” x 3.00” fractional 15 series rectangular T-slot profile with six open T-slots, two on each 3.00” face and one on each 1.50” face. The profile has align-a-grooves to assist in alignment when connecting profiles. The 1530 profile is compatible with 15 series fasteners. The center cavity of the profile can be pressurized up to 150 psi, lending itself to work spaces, machine guards, displays and panel mount racks.

I have certainly not tested whether the center can handle 150 psi! Probably not as this is plastic :)

The STL is in units of mm so should come out dimensionally correct with all the common slicers. It's 1" long, just scale in Z to the length you need.

Drawing dimensions here: https://8020.net/1530.html