Is zakat obligatory on a commercial shop for printing advertisements and commercials, and can it be estimated given the instability of income, knowing that the capital consists of a computer and a printer, and the work primarily relies on physical effort?

There is no Zakat on equipment, devices, and machinery if they are not intended for trade. Zakat is only obligatory on the income generated from them, if it reaches the nisab and a year has passed over it.

Zakat is only obligatory on items intended for sale, such as papers and inks.

At the end of the year, the value of papers, inks, and cash is calculated. If it reaches the nisab (equivalent to 595 grams of silver), then Zakat of 2.5% becomes obligatory on it.