"Catch as catch can" is an English idiom that means that something must be accomplished by any method possible. If a job or task is described in this manner, it may hint at a lack of planning on the part of the person doing it. The implication is that the way in which something is achieved is not as important as whether it gets done. This phrase gets its origins from the sport of wrestling, where a match without any restrictions on the types of holds that may be used is called a "catch as catch can" match.
An idiom is a short expression or phrase that may not mean what the words it contains suggest based on their literal definitions. Instead, an idiom can gain its meaning over time from the way it is used in a culture, even if this meaning has little to no connection to its literal origins. Using such phrases allows speakers to add some color and impact to their conversations with others. One such idiom is the phrase "catch as catch can."
Basically, the phrase means that a person doing something can take many different avenues to getting it done. As long as the thing gets done, though, it doesn't really matter what method was used. In this way, the phrase suggests that a person should be concerned with the results first and foremost rather than the means. For example, someone might say, "It was pretty much a catch as catch can job, but even though it was an unorthodox method, we got it done."
There is also often a connotation attached to this phrase that suggests that a job might have been done with little planning or foresight. When used in this way, the phrase implies that the people doing the job simply put their heads down and went to work until they were finished. As a result, the effort may not have been as efficient as it could have been, but it was nonetheless effective. Using this context, consider the sentence, "I built that deck with no instructions; it was pretty much catch as catch can."
In the sport of wrestling, the two combatants try to wrap each other up in a series of different holds. Many types of wrestling only allow certain types of holds, but "catch as catch can" wrestling has no such restraints. As a result, this phrase is often closely associated with the phrase "no holds barred," which also comes from wrestling.