Just received my arm locks from shapeways today. Every thing fit great, I didn't have to make any adjustments. Totally fixes the weak arms and I can have Devy hold up his arms above his waist. Thanks @Robots78 , this is a real creative solution. Kudos for designing this!

Now if only there was something we could do about the weak elbow joint...

 

So to make the pieces work for this other Devastator kit I have (the one with the shoulder extensions that look like treads and the very G1 Mixmaster cab) I just created and printed a rectangular prism 50mm x 21mm x 9mm with a 5mm hole 3mm from the 50mm edge (Numbers!). I need to dremel and curve the ends and make the hole bigger, but after I adjust it, it will hold Scavenger and Boncrusher's treads in place.

So thanks for making the base pieces I needed available!

 

Awesome! Please post pics when you have them done!

 

Had to make some alteration with ye old dremel. Will attempt to make the changes to the stl file in Sketchup at work on Tuesday (This is my first time 3d modeling anything).
If I am successful, I will post the file and you can offer it with your original design. I am just happy I made it work on mine!

 

No chance to get on sketchup today, but I did finish the prototype piece and it works perfectly on both arms using each of your pieces. Hopefully I will be able to model these. If not, I will send you the physical dimensions if you want to try modeling it. Will get pics of the prototype later.

FYI it's for this kit:

 

Okay, here we go.

Dev with the Perfect Combiner PC-06 kit. Looks great.


But the treads normally dangle in the armpits.
I "prototyped" this piece - meaning printed a rectangular block with a hole in it, realized the hole was too small and I had to shave a lot off the block. It attaches to the pegs on either of Robots78's add-ons and plugs into the insides of the treads to hold them snugly in place.



And it works! The treads are secured in place giving Devy some nice beefy arms.

My piece looks rough because it was more dremel work than 3d printing, but I hope to recreate it as an .stl so it prints without needing that much work.

 

Looks good!

What I have in mind for a "universal" fix will be pretty much like that but with slim pieces that will leave room for parts on the other kits like the one I have. (The shoulder pieces I have attach where your new pieces attach, so I have to work around that.)

Knowing that the Perfect Effect kit has that much empty space to work with is good to know. Now I need to do some research on the X2 kit shoulder pieces...

 

I will be excited to see what you come up with! Mine is very crude, but it worked for what I needed.