(commands used to generate the image above)

>    chargerand:= rand(1..100)/100:
for i from 1 to 5000 by 1 do
   rr:=5*chargerand():
   thet:=2*Pi*chargerand():   
   ppp[i]:=[rr*cos(thet),rr*sin(thet),20*(1-chargerand()^2)]:
   rr:=5*chargerand():
   thet:=2*Pi*chargerand():
   qqq[i]:=[rr*cos(thet),rr*sin(thet),20*(chargerand()^2)]:
end do:
p1:=pointplot3d({seq(ppp[i],i=1..5000)},symbol=circle,symbolsize=2,color=tan):
p2:=pointplot3d({seq(qqq[i],i=1..5000)},symbol=diamond,symbolsize=4,color=grey):
p3:=plot3d(5,theta=0..2*Pi,z=0..20,coords=cylindrical,color=black,thickness=2,style=wireframe):
display(p1,p2,p3,scaling=constrained);

>