What is the best way to put rubber bands on a 6 bar to help lift weight?
Pictures if possible please
google it idk.
I would start by identifying two points that are close together when the arm is raised but far apart when the arm is lowered and try those. If they don’t work, you can add more rubber bands or change which points you’re using.
But then ipthe rubber band would be loose when the arm is raises
If you think about it, you will realize that the greatest load on the arm is when it is horizontal. When it is nearly fully raised, you probably won’t need rubber bands for it to hold its position.
Then pick two points further apart. If you want something more constant (not necessarily something you want) there are several threads from last season discussing how to do this.
I just need something that will help support the weight of the cap, could rubber ands even help with that?
Yes i can get tou pictures tommorow but what we did was lifted the lift up and made a triangle so all the way at the top was an equallateral triangle. Also we have rubber bands on the back section that are in a straight line. It keeps the cap up at every point.
The first method I would suggest is doing the two-point method for rubber banding like such:
If you are unable to do that, you can compress the rubber banding to something similar to below. I would highly recommend having the point that the rubber band wraps around has the ability to turn as the rubber band stretches and compresses to decrease the amount of friction.
Hopefully this helps 
EDIT//: Image links didn’t load, fixed.
so should the rubber bands be tight when the lift is like the picture or loose?
When the lift is down as it is in the images, yes the rubber bands should have quite a bit of tension on them.
Here is a link to my favorite post on rubber bands: Uniformly Tensioned Rubber Band System Analysis / Guide