I have used many methods depending on the costume.
1 Push up or Water bras work very well. works with most covering outfits.
2 Taping can be very effective but it does hurt and requires you dont move your arms to much. can leave marks on you if you dont heal fast ,but i do heal fast and im quite tuff so i use this any time my chest is seen in the outfit.
3 large silicone boobs are great and some are even sticky on one side or the other. you still need a bra with most of these, they are expensive and will often pick up dye from the clothes so beware of dark clothes touching them.
4 when i was young i often used doubled up water filled 12 inch ballons, but its hard to make them perfectly the same size, and they dont last more than one night, you can use punching balloons if you need um to last a week. Or a pair of rolled up socks used with a bra.
Its not a problem to be off topic just so long as it is SFW (safe for workplaces discussion)