Singaporean father of three YJ works as a warehouse supervisor and used to earn an additional S$1,000 (US$730) a month setting up banners and dismantling fixtures at trade shows and events. That vanished when Covid-19 hit and international travel stalled last year.With Singapore now opening its borders to 21 places – offering vaccinated residents and tourists the option of quarantine-free travel – and the return of large exhibitions and conferences, the 49-year-old is hopeful that the lost work…