  In laboratory experiments we observe dust aggregates from 100 \mu m to 1 cm
in size composed of micrometer sized grains levitating over a hot surface.
Depending on the dust sample aggregates start to levitate at a temperature of
400 K. Levitation of dust aggregates is restricted to a pressure range between
1--40 mbar. The levitating is caused by a Knudsen compressor effect. Based on
thermal transpiration through the dust aggregates the pressure increases
between surface and aggregates. Dust aggregates are typically balanced 100 \mu
m over the surface. On a slightly concave surface individual aggregates are
trapped at the center. Ensembles of aggregates are confined in a 2D plane.
Aggregates are subject to systematic and random translational and rotational
motion. The levitated aggregates are well suited to study photophoretic or
thermophoretic forces on dust aggregates or the mutual interaction between dust
aggregates.
