After having arms slowly deflect up on me I began to look for a more permanent solution. There are several different types of aluminum and ABS models out there. I took my MK8 design, added the pin and tab found on Whpthomas's version, and made a few modifications to get it printable at Shapeways in stainless steel. I know there were possible tolerance issues considering Shapeways gives a very large tolerance. The part I received measured very close (within .15mm), If you have this made, bear in mind the possible tolerance issue.
I had front arm printed at Shapeway's
I printed off the back piece in PLA. I never see any warping on the back piece. It is basically a spacer and holds the spring. I also did not want to add the extra weight.
10mm M3 button head bolt
flat head m3 x10 bolt
compression spring. I am using this one a jones spring:
I bought the spring from mcmaster carr as part # 9657K333
This works just like all the other extruder modifications. I printed the pin upside down. It only lays a single circle on the first layer, but it printed fine because it is so small so it didn't fall over. Use the flat head on the top right of the stepper to hold the back piece on. The hole for the bearing screw I made purposely a little small so I could try to tap threads in it. It took threads but it is not something I would not trust it so I also put the nut on the back. Use one of the original bolts to hold on the arm with the pin placed inside. I put a little grease on the pin as well. Insert spring and bolt it all back together. It took up all the space available and I was going to print a slightly narrower back in order to give a little more space, but it has been printing for about 40 hours now without issue so I have not done that .