Line markings
There are a variety of temporary or permanent options for marking lines for the red and orange courts on full sized tennis courts.
Throw‑down lines
These are rubber or thermo plastic strips laid down on the court and can removed after each session.
Chalk
A mix of diluted chalk paint can be used to mark the temporary lines on both artificial clay and grass surfaces. Lime may be used to temporarily line red and orange courts on natural grass surfaces, but is not suitable for artificial grass courts.
Strong tape
Something similar to painter’s tape is semi‑permanent and will last up to six months.
Permanent paint
Semi-permanent paint can be used on artificial clay and grass surfaces. When using permanent or semi‑permanent lines, use a colour that is similar to the court surface so as not to distract players when using the full court.
Beach tennis 
The court is 16m long and for doubles matches, 8m wide and for singles matches, 4.5m wide.
The court is divided in the middle by a net suspended by a cord or metal cable attached to two net posts. The net is fully extended and is 1.7m high at all part of the net. A band covered the cord or metal cable and the top of the net.
The lines of the court are between 2.5cm and 5cm wide except for the baselines which are up to 10cm wide.
The lines at the ends of the courts are baselines and the lines at the sides are called side lines. The court boundaries are marked with a coloured boundary tape that contrasts with the colour of the surface and the court measurements are made to the outside of the tape.
Boundary tapes are produced specifically for beach sports and include rubber anchors or anchor plates to fix the tape to the sand.
Playing surface
The terrain is levelled sand, as flat and uniform as possible The surface is to be free of rocks, shell and other objects that could endanger or injure any of the players.
Junior beach tennis
16 and under and 14 and under
The court is 16m long and 8m wide. The net is 1.7m high across the full width of the court.
12 and under beach tennis
The court is 14m long and 7m wide. The net is 1.5m high across the full width of the court.
References
Tennis Australia. Court and Enclosure Dimensions.
https://www.tennis.com.au/wp-content/uploads/2012/04/Court-and-Enclosure-Dimensions-2012.pdf
Tennis Australia. Courts, Nets and Side lines 10-and-Under Tennis Rules.
https://www.tennis.com.au/
ITF Rules of Tennis. International Tennis Federation 2015. Nassau, Bahamas.
http://www.itftennis.com/home.aspx
Tennis play and Stay ITF Official Program
http://www.tennisplayandstay.com/media/124413/124413.pdf
ITF Rules of Beach Tennis
https://www.itftennis.com/beachtennis/tournaments/rules-regulations/rules-and-regulations.aspx
Sports association details