Case with a fat figure 8 shape

https://blobgarden.neocities.org/blob52/blob52.html

This is a hinged case based on a mathematically defined shape.

The outer shape is defined by the following equation, of the form f(x,y,z) = 0

(-0.18619E5)+(-0.228985E4).*x.^2+0.892569E3.*x.^4+(-0.5721E2).* ...
x.^6+x.^8+0.918261E3.*y.^2+(-0.558184E3).*x.^2.*y.^2+(-0.8971E2).* ...
x.^4.*y.^2+0.4E1.*x.^6.*y.^2+0.226969E3.*y.^4+(-0.779E1).*x.^2.* ...
y.^4+0.6E1.*x.^4.*y.^4+0.2471E2.*y.^6+0.4E1.*x.^2.*y.^6+y.^8+ ...
0.210743E4.*z.^2+0.11479E4.*x.^2.*z.^2+(-0.5771E2).*x.^4.*z.^2+ ...
0.4E1.*x.^6.*z.^2+0.849298E3.*y.^2.*z.^2+0.4842E2.*x.^2.*y.^2.* ...
z.^2+0.12E2.*x.^4.*y.^2.*z.^2+0.10613E3.*y.^4.*z.^2+0.12E2.*x.^2.* ...
y.^4.*z.^2+0.4E1.*y.^6.*z.^2+0.878329E3.*z.^4+0.5621E2.*x.^2.* ...
z.^4+(-0.355271E-14).*x.^3.*z.^4+0.6E1.*x.^4.*z.^4+0.13813E3.* ...
y.^2.*z.^4+(-0.355271E-14).*x.*y.^2.*z.^4+0.12E2.*x.^2.*y.^2.* ...
z.^4+0.6E1.*y.^4.*z.^4+0.5671E2.*z.^6+0.4E1.*x.^2.*z.^6+0.4E1.* ...
y.^2.*z.^6