The work was done in one stage according to the technology which/that the following card constitutes.
There are two problems with this sentence:
1. "...work was done in one stage..." can have two meanings. Either the work typically is done in several stages, but this time the entire project was completed in only one stage because of this special card; or it could mean that several steps are still in place, and the passage refers to one of those steps where work was done in a particular way related to the card mentioned, but in other steps work was done in some other, perhaps more conventional, way.
2. "Constitutes" means 'several things making up a whole'. A single thing like a card cannot 'make up a whole'.
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