Six legged walker with strong joints!

Step 3 Drill/overbore the holes, insert pipe, weld.

 So if you've made the walker already (like I did), then you overbore, if not, then drill out to slightly larger than the OD of your pipe. If you drill to the size of the pipe, you'll need to hammer in the inserts (as I did on the smaller/top end ones). 

Wash everything, then weld away. I TIG'ed everything, because the tolerances were tight, and I wanted it to be strong. A very good welder could use MIG... I don't think I could. If you don't have tig, perhaps gas welding or stick would be the next best? It comes down to you wanting a good weld with minimal excess fill sticking up top to grind off, then sand it smooth so it doesn't interfere with the washers. 

If you get much metal slumping inside the pipes, you may need to bore out the holes. If so, i'm sorry, because that will suck. Just use a lot of cutting fluid.