An insight to concrete planters

Here are some simple steps to creating a concrete planter yourself, although I have found this to be a one time production as the mold is only good for one go.

Step one: make a wooden or acrylic shape mold.  I have found acrylic glass held together with caulk or some other kind of easily removable sealant to work best, but wood and wood glue will work as well.
(You can also add other details such as a window, copper drain pipe, etc. to your concrete planter/building)

Step two: mix your concrete.  Portland concrete works best, and there is even a hardener element you can add to it to increase the strength.  I would suggest having at least 1/4" width minimum for all walls and the base.  Be sure to add some kind of slick element such as cooking oil to the sides of your mold before pouring in the concrete.

Step three: Pour your mold.  Add in your other elements to the side walls as you are pouring to make sure they are positioned correctly.  I would lean towards the watery side on your concrete mix, somewhere around the constancy of oatmeal.

Step four: Let your mold dry, it usually takes 2-5 days depending on where you live.  Remove your mold (often by destroying it) and plant some plants!