Dream time I believe is the time when the mind shifts from the perception of the macrocosmic existance of this reality to that microcosmic realm of one's own inner reallity. Your universe within the universe. In essence one's dreams can be said to be the equavilant of a sacred circle. One that a magician may cast before doing a ritual. As with circles awake the magician may enter a trance or altered state of mind specific to the ritual. Dreams automatically put the mind in a trance state. If one is capable of being concious within dreams they can utilize this trance state from their own ritual purposes and with the vividness of being able to utterly control the environment around them. One does not simply vizualize things within dreams they materialize. Its quite simple really. You're within a lucid dream you've had expirience manipulating what is around. You may even be at a point where you have your own inner temples. So you have a desire for a certain object or place or person and you can it forth. By sheer will. Within your dream you materialize what is desired. You can expereince it. As in touch it and use your senses to understand what is before you. Within dreams what you materialize will be of your inner reallity. To control the things you materialize will take practice. For example you can summon a sword but since it will be of your mind what you get may include certain aspects of your subconcious. Notice these things and see how significant they are. If they are immaterial to your intentions Gentally will them away. Like a sword smith you can temper the sword and use a hammer to shape it as you wish. The things you see that are important to your intentions can molded into asthetically pleasing shapes or jewls. You can shape designs, sigil and mantras in gold or plantimum to create you very own tool as it is your to make. Your mind will automatically remember this and in the future you recall this specific tool and use it in your own dream cerimonies.

Should you wish to place yourself within a specific environment alter the place as you did the object, or sword that I used for example. Explore the terrain and see the things that you didn't expect that your subconcious placed. If they are immaterial to what you are doing, get rid of them. Only keep the things apply. And you can create a place that is specific to your intentions that can also be recalled. Technically the things you materialize within dreams can be recalled/summoned by your own will. But a key phrase or sigil can also be used to aid.

Most things you materialize will only take seconds to do so. If your sub-concous alters it it will be obvious. So there is little need to spend lots of time compulsively dwelling on one object. As you get better it'll be easier to summon several objects at a time. Like five candles. Or a staff in one hand and sword in the other. Once you have the objects you need for a ritual you can preform magick in the exact same manner you would while awake. Probably the most impressive use of these tools, and more reason to have mantras/sigils to aid in summoning them, is that if you have skills visualizing you can use these mental creations awake in this world.

A note on subconcious alterations to what you create. The mind is your guide in the dream world. If your mind presents you somthing that you did not expect pay attention to what this is. While it may not apply to the object/place/person in question it may be related to something else important that may help or hinder you should you pay attention. These subtle changes can manifest at any time. And if you leave them unchecked they will turn negative and have an adverse affect on your workings. Listen to yourself for its the greatest guide you have.