Which preposition to use with brickmaking

for Occurrences 1%

Some one jumped off, and scrambled up on his hands and knees; his horse was driven up the bank to himon its knees, likewise, more than onceand caught staggering among boughs and mud; and by the time the whole cavalcade was over, horses and men looked as if they had been brickmaking for a week.

Which preposition to use with  brickmaking