Adding a new plane and linking its position to half the width of the box will work too. Mid Plane just saves you that step. For an example, here's the file with a Mid Plane extrusion and a guess at the size of the bosses that are mirrored.
From the curved shape I'm guessing that this box will be 3D printed.
Ah. I get it. You aren't moving my part. You're doing it mid plane from the first extrusion. For some reason I thought you'd moved it.
Thanks.
And yes. The original was and this one will be 3D printed.
Annin Robotics -Open source affordable robots - build your own 6 axis robot.
www.anninrobotics.com
You can see it behind the main axis. In my case I'm building the AR3 with external CUI encoders and using 6 pin 12mm aviation connectors instead of RJ connectors. The motors are also using the 12mm 4 pin connectors instead of the 16mm.
And I have thought about using this drawing to create a sand core and casting it in aluminum. Might do that at some point but I'm casting most of the pieces instead of buying expensive flat bar stock. Instead of $45 for a 1/2" chunk of plate I'll pay for $1.50 worth of Natural Gas and some scrap aluminum. Have to machine it in either case and if I screw up I can melt it and try again.
John