A vinea is another name for a penthouse. Penthouses were a means by which those besieging a fortress or castle might get to the foot of the walls in order to attack it, perhaps by undermining the walls or by filling in the moat to allow a siege tower to approach. It was basically a movable shed, made of wood and usually covered with raw or treated hides (and very occasionally metal plates) to prevent it from being set alight. It would have been on wheels and pushed up to the walls with the men inside so that they could do their work with some degree of protection. Obviously, the besieged would be busy trying to destroy this machine, preferably with fire.
This LW model is a simple box affair with a flat roof and two axles. It measures about 4 metres long and 280cm wide to scale, so room enough for a small wrecking crew. The sides are vertical planking with two small windows down each side. The front is similar, but with one wider window, perhaps an aperture for a battering ram. The roof has been moulded as being covered with skins, as it should be. However the very fact that the roof is flat would be highly unlikely, as it would invite missiles and fire to land and stay put, destroying the machine easily.
Zvezda did a very nice model of such a device in their Siege Machines Kit 2 set which included a battering ram, and it is just as well, because this LW kit is rubbish. It has three sides, a roof and two axles - not a lot of parts really, and yet nothing fits well with anything else. If the scan above looks wonky that's because it is. None of the sides are square with each other, and the pegs that fit the front to the sides are considerably closer together than the holes into which they are supposed to fit. Because the sides do not match, the axles are at an angle to the rest of it, making a very odd looking vehicle. There are also two pegs on the roof that serve no purpose whatsoever. Finally, absolutely all of the pegs are too large for their holes, even where they (more or less) line up. We had to trim all the pegs, enlarge the holes in the wheels, and completely strip some pegs simply to get the thing built in the very untidy manner you see above. By ignoring most of the pegs and gluing all parts in their correct position a rather better job could have been made of this, but we decided life was too short to spend so much time on so small a project.
Properly engineered, this little kit could have produced an attractive vehicle for any medieval siege diorama or wargame. However the placing and sizing of pegs and holes makes this far more difficult to construct than it should be, and with an unsatisfactory result.