mujoco

<mujoco model="Particle">

  <include file="container.xml"/>

  <size memory="1G"/>

  <option solver="CG" tolerance="1e-6" timestep=".01"/>

  <worldbody>
    <replicate count="10" offset=".07 0 0">
      <replicate count="10" offset="0 .07 0">
        <replicate count="10" offset="0 0 .07">
          <body pos="-0.35 -0.35 0.65">
            <joint type="slide" axis="1 0 0" group="3"/>
            <joint type="slide" axis="0 1 0" group="3"/>
            <joint type="slide" axis="0 0 1" group="3"/>
            <geom size="0.025" condim="1" priority="1" rgba="0.8 0.2 0.1 1"/>
          </body>
        </replicate>
      </replicate>
    </replicate>
  </worldbody>
</mujoco>