Making political signs is not an easy task at all as even if you have political agendas that need to be addressed, you cannot use it for the wrong reasons. Making such a sign is similar to making any other campaigning sign or hoarding but here only the physical method of making it would be the same. As far as the content of the signs are concerned they would be different. They are used to show either dissent or support and although the materials from which they are made are not very significant, what they depict is indeed important. but you also have to be sure about not using any indecent or unsuitable content.
Again, Political yard signs are of two types. There are the ones which are impromptu handiworks of the people who go out is rallies and marches on their own or to show their support for a party or an individual. On the other hand, there are the ones professionally made which goes up on the streets during any major political event. These are generally made according to the specifications of the individual and the party and before they are put up, they are approved by everyone concerned. The impromptu signs are more or less made by the people, at their own discretion and messages are either printed or even hand written. They are usually made from materials like cardboards and the like.
Which ever variety is used, they are not very expensive to make. With easy access to technology and with the advent of things like digital printing, it has become possible to make hoardings and signs in short notice. The most important thing is that these professional signs are made from superior quality materials which are resistant to rain and harsh sunlight and also to the dust and pollution. No wonder that they can be put up for long stretches of time. Of course they may sometimes come apart with sudden winds but otherwise they are indeed resistant. They screens are made from strong polyester. No wonder that they are used even for smaller political events these days.