If one is a little crazy and committed to putting on Harper's Ferry, one could go to the extremes that I did a few years ago. I wanted to field a Harper's Ferry game. I studied the history of the event and made some compromises for gaming purposes. If there had been buildings available at that time, it would have made my life much simpler.
The figures were selected from various manufacturers and converted as needed. The scenario was for John Brown and his named associates to capture the arsenal (25). Then, the alternate history started. While the various militias arrived each turn, responding to calls for help from Harper's Ferry, bands of "revolting slaves" (99) also arrived to assist John Brown. There were also 30 more Brown's associates in three units that were fighting in the game.
The game board was 16' by 6' (4 - 4x6 panels) and included over 40 buildings. There were 5 levels at 2" each to reach the highest point above the town. I generally followed the period map of the town to lay out the game board. The foam panels used for the board were sculpted with heat tools and finished with latex paint and copious amounts of Woodland Scenics materials.
Approximately 10 buildings were purchased, ACW period, cast, painted buildings. The rest of the buildings were all scratch built. Having visited the town more than once, and with access to period photos, I tried to make buildings in the style of the period (and to be used for ACW gaming later). The arms work, the arsenal and fire house, Washington's nephew's home and various shops, homes, stables and commercial buildings were all constructed over a few months. I used Grant Line windows and built the buildings from Masonite, plywood, wood strips and cardboard.
Brown and his men and the revolting slaves were charged to hold the arsenal and take out the telegraph office. The other men with Brown and more of the slaves were tasked to capture wagons in town, and then the weapons at the arms works and capture Washington's nephew and the great man's sword and return to the arsenal. Once back at the arsenal, the entire Brown contingent was to exit the board, over the bridge.
The game began with Brown's attack on the arsenal and capture of the (iconic) fire house. The 12 units of militia and 2 units of armed townsfolk gradually mobilized and arrive on turns in the beginning of the game and conflicted with elements of the Brown contingent. Late in the game the Federal troops (with Lee) were scheduled by turn to arrive. So the Brown contingent had to accomplish their tasks and move on (off the board) to avoid fighting the Federals.
During the game there was quite a bit of street to street fighting between the groups moving through the roadways of the town. The arms works were located at the end of a road, to simulate the distance to reach it. Likewise, the home of the Washington nephew was also situated in the same way to isolate it from the rest of the table.
This game has been run twice at conventions for ten players. The scenario has worked well, but the Brown contingent has never completed all their objectives. The game has resulted in a great many casualties in the first 10 or so turns. But once the cavalry arrives across the bridge, it became very "bloody" for Brown's party.
I will try to find and scan in some pictures that were taken of the game. I did not include the train tracks in the setup, but some participants "arrived" at the train station which was represented. Also, the bridge was not represented except for the location on the table where it was an entrance point.