To expand a bit about this interesting topic, here's something I previously posted in my Coven forum:
First of all, what is an Astral Temple and what is its use?
Firstly, the name really is misleading, because it's not really on the astral plane but in your mind. You are your own temple. However, due to the very nature of the Astral Plane, you can create your temple there once you've created it in your mind. Like anything in the realm of mind or astral, this requires constant maintenance. So maintain your Astral Temple at least once a month at a minimum.
So what is the purpose of this temple? Well, it can be used for anything you need it for. Whether it's for ritual, just a quiet place to get away to, spells, talking with other entities in a safe location (such as spirits). Whatever you desire to use your temple for is up to you.
Creating your temple
Start by drawing out a rough idea or writing out a general list of attributes you'd like your temple to have. Does it have walls or is it a labyrinth? Do you want it to be a sacred meadow surrounded by high stone walls or a small cottage? These are all things you need to consider.
Next, think about the materials that you would need. Do you want it made from stone, brick and mortar, a thatch style, the elements, etc?
Now think of a key style you want to use. This is not to be told to anyone, otherwise you will have to rethink it and remake your lock for your temple.
This is the fun part. Visualize all of this. Start by visualizing your area. Whether it's in a meadow, in a bog, whatever. Start building your temple "brick by brick". You want to make sure your foundation is out first so that you can build upon it, this is no different than your time in your path. You need to lay your foundation and build upon it.
The next thing you need to do once your entire temple is built up, is go through it. Walk through the door of your temple, and make adjustments as you go. You can now create your altar, add carpeting to the floor (if you have one), whatever it is you desire.
Remember that you can come back to this place just by thinking about it. It will change as you change and as you want it to change. You can invite your friends, or create thought forms here. It really is a free for all on your part.
A few things to remember: Meditation is key for concentration so your temple is not a ghetto, unless that is how you designed it to be. It's important to keep it clean and free of clutter. Be focuses on what you want, and creativity is important because your temple is you.
A Clean Aura is a good idea, as well as cleansed and balanced chakras, but you can also do that in your temple. ( I personally have a special place in mine for healing and cleansing, this is a personal option that you can choose.)