Set of three extensions for simple IKEA Albert book case (https://www.ikea.com/pl/pl/catalog/products/00111994/).
The set consists of two kinds of Feet (good for protection from weather in outdoor scenarios or from an oil spill in a garage). Short one for regular setup and long one for modified setup with shifted up shelfs (to acheve one more space at the bottom). Duo and Tri Hook for obvious purpose. I have added also a Connector which dont look very usefull (to connect two book cases), but I have seen not so sophisticated livehack (youtu.be/6a5P3jSkyD8) of cutting bookshalf in half. So if You change your mind You can always use a Connector (dont forget to screw it for safety reasons).