In this page I hope to provide an example of one way to reconstruct a festival about which relatively little is known in hopes of demonstrating that with a healthy blend of research and creativity it is possible to carry forward the spirit of ancient traditions in a modern context in a respectful and meaningful way. In this case, little is known about the Hephaisteion festival beyond its name and that it took place on an unknown date in Athens in honor of Hephaistos. Because of what we do know about Hellenic festivals and about the deity honored in this particular festival, we can fill in the blanks with a surprising amount of detail.
Hephaistos (also Hephaestus, adapted by Romans as Vulcan) is a unique and multi-faceted deity among the Olympians. Commonly associated merely with blacksmithing, he has been known to patronize craft and innovation, to command and personify fire, and to demonstrate unique grace and innovation. He is said to have been born of either Hera alone or Zeus and Hera together. Although details vary between stories, one of his parents hurled him from the heavens to the earth below, where he was taken in and cared for by others, even hidden away for his protection. By this point, he was at least partly lame and somewhat disfigured, although extent and detail varies in different stories, places, and times.
In the course of time, he became a valuable part of the Olympian throng, even being called upon to handle delicate and important tasks for Zeus and others. He has had one or more wives/mates (as always, depending on the particular myths), such as Aphrodite, Athena (major technicality in this case!), one or more of the Graces, etc. An impressive list of mates and offspring may be found at the Greek Mythology Link, which provides more information in one place about the lineage of Hephaistos than I have found in any one other place on-line.
He seems to have been celebrated in relatively industrial areas, such as Athens, Sicily, and Lemnos. But in more rural and agricultural areas, we know of no major temples to him. Two festivals dedicated to him in Athens are Khalkeia and Hephaisteion. Khalkeia was a crafts-oriented festival devoted to Hephaistos and Athena, who shared a temple called the Hephaisteion. The two deities are associated in a few ways:
When Zeus consumed one of his mates to prevent her giving birth to Athena (in an apparently successful attempt to circumvent a particular prophecy), he needed some assistance to complete the highly irregular process of giving birth through his head. Hephaistos was chosen above all other Olympians for the task. When Zeus commissioned the creation of Woman according to precise and exacting specifications (including that Man find Woman irresistible), Hephaistos was again the natural choice.
Hephaistos works with a variety of materials (although he is best known for metalwork) to craft the thunderbolts of Zeus, scepter of Hermes, shield of Agammemnon, and many other marvelous things (including many living things that would normally be inanimate, such as statues, tripods, and pillars). He is even able to produce devices fine enough to trap one or more other gods beyond their ability to escape without his aid. In the article Craftsmen Figures of Greek Mythology, Jeremiah Genest even draws some fascinating connections possibly identifying Hephaistos with Ouranos. Hephaistos is clearly a god capable of harnessing and manifesting considerable power beyond the expectations of those who think of him as merely a lame god of blacksmithing. He is said to be able to cause his equipment to function without his manual operation, and to manifest himself as fire and the master of fire in battle.
We do know that torch races were common not only in ancient Hellenic festivals generally, but also specifically in festivals devoted to Hephaistos, a fire god. Sacred drama and the recitation of hymns and myths are also common elements of Classical festivals. Processions, offerings of certain kinds, and purifications are essentially standard parts of all Hellenic festivals, as well. It is not uncommon to have an annual festival attending, at least in part, to the physical maintenance of the shrine, temple, or icon of the god.
One common means of purification is by fire, which can be applied in various ways. For instance, a torch or other flame may be held under or near participants, or a log may be taken from the fire and used to sprinkle water around the perimeter of the festival area and on the participants. Since Hephaistos is a fire god, a fire purification seems appropriate.
Homeric, Orphic, and modern hymns to Hephaistos are available for reading. He also features in numerous myths, making it quite possible to piece together any number of brief stories of Hephaistos appropriate for ritual (enough to allow for a completely different story annually for several years, in fact). The festival may also include a ritualized activity of shrine maintenance.
So one possible reconstruction of Hephaisteion could involve a procession toward the local Hephaistos shrine, a fire purification, the singing of hymns to Hephaistos and a torch race in his honor, libations to him (and to Athena or other figures associated with him, as deemed appropriate), and a sacred drama about him (which may be performed by one or more people).
Particularly if you lack the resources to maintain a dedicated full shrine to Hephaistos, you may wish to keep a small figure representing him in a sturdy enclosure (like a really nice wood or stone box), and re-enacting pivotal events in his life with it. I've got a few different ideas of some of the details, but one is to craft the figure before the festival itself and place it in an enclosure in the shrine area.
During the telling of his story, the figure is taken out of the "box" to represent his birth from Hera, and cast down & broken (as in the myth). Either the broken figure would then be repaired, or a new one crafted (or pre-crafted and used at the appropriate time, depending on local logistical concerns), re-enacting the part of the story where Hephaistos is cared for by the people of Lemnos, Dionysos, and others.
The final figure would be placed back in the enclosure in a place of honor at the shrine, representing how his caretakers hid him for his safety, as well as representing his residence and workshop in the fiery earth. After the Hephaisteion festivities are ended, the enclosure could be put some place safe until the following year's festival. In the case of a full-time shrine to Hephaistos, it could remain in place for the year. It could, of course, be used for personal devotions to Hephaistos as well. When all is done, enjoy some feasting and the company of those who share in the festivities.