Plastic shims?

[Snake_Eyes]

Here are my measurements...

Left to right- off by 1/4" right side is lower
Left side front to back- off by 1/8" back is lower
Right side front to back- level

Can I just slide 2 or 3 shims on the right side and a couple on the back left corner to raise it up?

my tank for reference

 

[fishdance]

I dont know what material your plastic shims are made of but I use the white chop board plastic to waterproof the bottom legs of many of my wooden stands. Cut into suitably sized rectangles and slipped under each leg to keeps the wood out of any free standing water. Most of my stands are 3 and 4 tiers of tanks high and I have never had any problem with using them.

 

[509stinger]

for the tank i'd use 1/4" foam sheet and for the stand i'd go with the plastic shims as long as they won't be visible from the common viewing side, but thats just me.

 

[Snake_Eyes]

The shims being visible won't be a problem because of their small size and color. Would I need to do the foam since the shims should level it out?