Why would someone want a portable chicken coop? There could be any number of reasons, including the need to transport your chickens and not wanting to put them in a Rubbermaid container. You might also need to move your coop around the yard quite a bit, and honestly, portable chicken coops can be made in just about any size you could imagine.
When it comes to the portable chicken coops, there are indeed a few things you will need to consider. First of all, you need to make sure the chickens can move in and out easily. You also need to make sure that there is a place for food and water within the coop. Remember that portable shouldn't mean cramped.
When you are creating any sort of portable chicken coops, it is important to have some sort of transport system built in. Normally people will use wheels, and with that being the case you will need to choose wheels that are of appropriate size for your enclosure. The wheel actually isn't the issue, it's more an issue of the axle size and it being crushed by the weight of the coop.
If you have a smaller chicken house, then you need to make sure that you streamline the exit process from the interior of the coop to the exterior yard. You don't want them to become stuck because chickens tend to panic when they are stuck. When you are dealing with such a confined space, the last thing you want is a group of chickens freaking out inside the coop because it can lead to serious issues such as the chickens breaking their necks, damaging each other, or damaging the coop in general.
Larger portable chicken coops are easier to build because you have more room to work with. You could even put a window or a rear access point into the coop. These types of portable chicken coops will usually need to be towed with a trailer, though if you need to move them a very short distance you might be able to do it by hand.
If you are going to build one of these then you need to get your hands on a good set of blueprints. You could just do it by ear, but chances are you will just run into a load of problems when doing that unless you are an experienced construction worker or have done this sort of thing before.