I would work on a fire starting technique which doesn't rely on airflow from wholes in the bottom.

• Basically use any technique that you would use in an old-fashioned chimney or a campfire on flat ground - in both cases you have to make due without venting from directly below.

While creating wholes would certainly help, it would also create problems:

• Ashes, embers, coals, etc. would fall through while using it. To avoid damaging whatever you use the fire bowl on you'd have to add some heat-resistant container to catch them.
• As @JamesJenkins mentioned, drilled wholes will speed expose the non-coated core of the bowl, and thus allow for rust.
• Last but not least: you'd have to make quite a bunch of wholes to get a lot of airflow, at least if you're not paying a lot of attention to fire starting/building technique. And if you are, I'd say there shouldn't be any air flow problems even without wholes. :)

I would work on a fire starting technique which doesn't rely on airflow from holes in the bottom.

• Basically use any technique that you would use in an old-fashioned chimney or a campfire on flat ground - in both cases you have to make due without venting from directly below.

While creating holes would certainly help, it would also create problems:

• Ashes, embers, coals, etc. would fall through while using it. To avoid damaging whatever you use the fire bowl on you'd have to add some heat-resistant container to catch them.
• As @JamesJenkins mentioned, drilled holes will speed expose the non-coated core of the bowl, and thus allow for rust.
• Last but not least: you'd have to make quite a bunch of holes to get a lot of airflow, at least if you're not paying a lot of attention to fire starting/building technique. And if you are, I'd say there shouldn't be any air flow problems even without holes. :)