mujoco

<mujoco model="100 sphere meshes in a box">
  <option solver="CG" iterations="10"/>
  <asset>
    <mesh name="sphere" file="sphere.obj" scale=".1 .1 .1"/>
  </asset>
  <worldbody>
    <geom name="ground" type="plane" size=".5 .5 .01" condim="1"/>
    <replicate count="4" euler="0 0 90">
      <geom type="plane" size=".1 .5 .01" zaxis="1 0 0"  pos="-.5 0 .1"/>
    </replicate>
    <replicate count="100" offset="0 0 .5">
      <body pos="0 0 1">
        <freejoint/>
        <geom type="mesh" mesh="sphere"/>
      </body>
    </replicate>
  </worldbody>
</mujoco>