For alternative, you can use 1-gallon plastic pot, so it will be easy for you to measure the soil moisture and soil field capacity for the drought experiments.
For Zea mays (maize) and Phaseolus vulgaris (common bean) at the four-leaf stage, pot sizes ranging from 0.5 to 1 liter are commonly used in greenhouse experiments studying drought stress. This size allows for sufficient root development while still maintaining manageable conditions for experimentation