Since you mention Mathematica, I will use it to provide some more examples for various t values. However, I can not help you with the canvas.
This is the Mathematica code:
With[{a = 3, t = 0.7},
RegionPlot3D[
10^-(t x + y)^10 + 10^-(-t x + y)^10 + 10^-(t y + z)^10 +
10^-(-t y + z)^10 + 10^-(t z + x)^10 + 10^-(-t z + x)^10 >
5/2, {x, -a, a}, {y, -a, a}, {z, -a, a}, PlotPoints -> 50,
Boxed -> False, Axes -> None
]]
t = 0.2

t = 0.4

t = 0.7

t = 1
