Ec0-bricks are easily made from 2litre coke bottles, which you fill with non recylcable plastic. Push it down until the bottle is jammed hard. They are then used in construction of creches, homes etc. Here are the instructions.
https://ecobrickexchange.org/views/home.php
Find out where you can drop off your filled Eco=bricks
Green pop Nursery, Woodstock
Cobute, Table View
Hangar 18, Milnerton
Faithful to Nature, Muizenburg
Salt, Kalk Bay
The health connection, Fish hoek
The daily Grinder, Glencairne
The Hub, Scarborough
Long Beach mall, Noordhoek
MFM radio, Stellenbosch
For others cities check out https://ecobrickexchange.org/views/home.php