Proper Klingon Kleavage is just a matter of physics. Or more specifically, mass displacement. There are many different ways to lift, push, or smush without getting arrested for indecent exposure.
Also commonly called the "Clams on the Beach" effect. This cleavage can be achieved with many different methods. These are all based on the same principle... if you push breasts straight in, towards the body, the tissue has to go somewhere. You've just got to aim it where you want it to go.
This can be done with a corset under your clothes or in the top itsself. If you do not have access to historical corset patterns, try the bridal sections of any major pattern company. (McCalls, Simplicity, Vogue, etc.) Look for dresses that have lots of vertical seams in the bodice. These are usually places where boning has been inserted.
Just remember boning is your friend. Just as any house needs framing, so does a proper corset. In today's world you don't use whale bone anymore. Metal boning is available from specialty stores. And plastic boning should be available from most fabric stores.
Frederick's of Hollywood is my new friend. They came out in the Spring of '98 with a "wench corset" that is almost historical. The materials are modern, but the construction is classic. And it came along just in time for me to do the first Klingon assimilated by the Borg, 6 of 9. The reflective house numbers are from Hechingers, a Washington DC hardware chain.
A few years ago, the undergarment world was revolutionized by the introduction of the Wonderbra©. After years of minimizing and separating, the industry standard is to maximize and push-together. The recipe for perfect cleavage.
But unfortunately, for some of us, the Wonderbra© does not fit. There are ways to create the same effect using regular bras.
First of all, get yourself correctly measured! Your chest size is the measurement around the ribcage under the breasts. Then measure around the fullest part of the chest. This is the bust.
Band size depends on the maker. Some use the chest measurement as the band size. Others add 4 to 5 inches. I personally am more comfortable by adding. But I use the chest only version for enhanced cleavage.
To find your cup size, subtract the band from the bust. 1 inch=A, 2 inches=B, 3 inches=C, 4 inches=D, 5 inches=DD, larger depends on the maker. Since you can't smush your ribcage, the adjustment is in the cups.
The affect to the left was done by taking a bra of the correct chest size, but 2 cup sizes smaller than normal. Normally I dislike underwire bras. (Wires jamming into one's ribcage every time one sits down is not pleasant.) Overfilling the cups seems to have the effect of lifting the wire away from the body, and thus no jamming.
For those smaller than a C cup, there's always padding. You can go with the classic tissues in the bra. (Handy during hayfever season.) Or try one of the many pads or "falsies" on the market. Most can be inserted into regular bras. To keep the natural look, make sure the padding is under and to the sides of your real breasts. (By the way this is what Wonderbras© do. What did you think those "biscuits" were anyway?)
Jog bras are the modern equivalent of a flat front corset or of binding the chest. They smush ya up & hold ya there. Again, go for the correct band size then size down or pad from there. Just be warned, not all jog-bras hold alike. I had a recent experience were every time I moved, my chest took on a life of it's own. There is now video of the nose-knees maneuver.
It doesn't matter whether you're talking about adhesive cups, medical tape, or even handy-dandy duct tape, it's all sticky tape. Tape is for when you can't wear a bra (backless or very low cut outfits) or the outfit isn't substantial enough to hold you up.
Imagine trying to tape a water balloon up on a wall, and you've got the approximation of how to tape up cleavage. Basically all you can do is hold the breast where you want it, and tape up. Lying down sometimes helps. Or you can have a buddy tape you, if you're not shy.
Just remember that what ever you put on you've gotta take off. You know what you have to go through to take a band-aid off? Imagine that 10 times bigger & doing it twice... on slightly more sensitive skin. "Ouch" doesn't begin to cover it.