Mark tier for push-in pillar placement. Use the separator plate for the next tier above, gently pressing it onto the tier, feet down, making sure it is centered. Lift plate away. The feet will leave marks on the icing to guide the position of pillars when you assemble the tier. Repeat this process for each tier, working from largest to smallest tier. The top tier is left unmarked.
Place each tier on its separator plate, securing with icing.
Position push-in pillars at marks, and insert into tiers. Push straight down until pillars touch the cake board.
To assemble, start with the tier above the base tier. Place the feet of the separator plate on the pillar openings.
Continue adding tiers in the same way until the cake is completely assembled.