Top and Bottom Plate
Andy Berger replaced the top and bottom plate with 2mm aluminum plate (https://www.facebook.com/groups/101herounofficial/permalink/1212951378782424/)
Some people just use superglue with wood bar.
My solution is insert 6 aluminum bar into the gap of the pylon. You can use any method you like, just to make sure the distance between the 3 pylon is fixed and will not move during printing. This upgrade cost me $0 as the aluminum bar is the remaining parts from my old curtain.
Diagonal Push Rods
Stefano Marcon replaced it with the carbon fiber arm.
Other people use elastic band or light weight springs to pull the arm to the ball join
|Elastic band by Stefan-Gautsch - Spring by David Leeds|
I am using the idea from David Leeds who glued a 2mm carbon fiber rod to the arm and attached weak springs to them. This upgrade cost me $4 for 4 x 1 meter carbon fiber rod and $1 for 8 springs. I just used one rod and still have 3 remain. This solution provide similar improvement as the carbon fiber arm but much less in cost.
For the remaining carbon fiber rod, you can also use them to strengthen the structure of the triangle plate as what David Leeds did (https://www.facebook.com/groups/101herounofficial/permalink/1225738600837035/)