A method of forming a layer for an electronic device on a substrate, the method using a print head having a plurality of nozzles to deposit an aggregate volume of ink onto each of a plurality of target regions of the substrate, the aggregate volume to be within a predetermined volume tolerance range, each of the nozzles generating at least one respective droplet volume, the method comprising: for each nozzle, receiving information representing an expected droplet volume for a nozzle firing waveform, the expected volume based on an empirical determination of the droplet volume by a droplet measuring device; for each of the target regions, calculating a respective plurality of combinations of droplets for each of which combinations, corresponding expected droplet volumes sum to a value restricted to be within the predetermined tolerance range, the calculated combinations including a first combination associated with a first target region and a second combination associated with a second target region; and generating control data for the first combination and the second combination, the control data sufficient to: instruct relative motion between the print head and substrate to concurrently bring at least one nozzle associated with each of the first combination and the second combination respectively into proximity with the first target region and the second target region, the relative motion comprising a sequence of scan paths, the scan paths being offset from one another according to a sequence of variable-size geometric steps, and instruct firing of the at least one nozzle associated with each of the first combination and the second combination to concurrently deposit one or more droplet volumes respectively in the first target region and the second target region, wherein generating the control data further comprises selecting, from the calculated plurality of combinations, the first combination and the second combination, the selection of the first combination and the second combination being such that at least one nozzle associated with each of the first combination and the second combination may be fired concurrently to deposit one or more droplet volumes respectively in the first target region and second target region. for each nozzle, receiving information representing an expected droplet volume for a nozzle firing waveform, the expected volume based on an empirical determination of the droplet volume by a droplet measuring device; for each of the target regions, calculating a respective plurality of combinations of droplets for each of which combinations, corresponding expected droplet volumes sum to a value restricted to be within the predetermined tolerance range, the calculated combinations including a first combination associated with a first target region and a second combination associated with a second target region; and generating control data for the first combination and the second combination, the control data sufficient to: instruct relative motion between the print head and substrate to concurrently bring at least one nozzle associated with each of the first combination and the second combination respectively into proximity with the first target region and the second target region, the relative motion comprising a sequence of scan paths, the scan paths being offset from one another according to a sequence of variable-size geometric steps, and instruct firing of the at least one nozzle associated with each of the first combination and the second combination to concurrently deposit one or more droplet volumes respectively in the first target region and the second target region, wherein generating the control data further comprises selecting, from the calculated plurality of combinations, the first combination and the second combination, the selection of the first combination and the second combination being such that at least one nozzle associated with each of the first combination and the second combination may be fired concurrently to deposit one or more droplet volumes respectively in the first target region and second target region. instruct relative motion between the print head and substrate to concurrently bring at least one nozzle associated with each of the first combination and the second combination respectively into proximity with the first target region and the second target region, the relative motion comprising a sequence of scan paths, the scan paths being offset from one another according to a sequence of variable-size geometric steps, and instruct firing of the at least one nozzle associated with each of the first combination and the second combination to concurrently deposit one or more droplet volumes respectively in the first target region and the second target region, wherein generating the control data further comprises selecting, from the calculated plurality of combinations, the first combination and the second combination, the selection of the first combination and the second combination being such that at least one nozzle associated with each of the first combination and the second combination may be fired concurrently to deposit one or more droplet volumes respectively in the first target region and second target region.