There's simply not a better exercise for the triceps than the board press. In order to fully recruit and tax all the targeted fibers of the triceps, both research and experience have shown us that very heavy weights need to be employed to build lockout.
Your triceps are limited by the poor leverage at the bottom end of complex movements like bench press and close-grip bench press. The isometric contraction of the triceps in the stretched position throughout the lower end of the range of motion (before the triceps are called on to lock out a weight at the top) further limits maximum contraction. Even though isolation movements like dumbbell extensions, skull crushers, and pressdowns have some place in triceps training, the limiting factor is the poor leverage of the triceps at the elbows when flexed beyond the 90 degrees position.
The overload allowed by the shortened range of movement in the board press has no competition for yielding tremendous results. Weights in the vicinity of your raw bench press 1RM can be used for reps with 3-5 boards and a wider grip. Likewise, you can do reps with your close-grip max on a 2-3 board with a close grip. It isn't hard to figure out why this works for both strength and mass.
To do the board press, you need some boards. You can duct tape a phonebook if you want to save the redwoods, but I don't recommend it. You can use either 2 x 6s or 2 x 4s from 12 to 24 inches long. I buy mine in the cull wood section of Home Depot. This is the cheap, throw-away wood available in the back of the store. I build all my boards and boxes for box squats out of this material.
If you train alone or with only one spotter, keep the boards closer to 12 inches long so you can stick them under your T-shirt or secure them to your chest with a belt or knee wrap. If you have more spotters or partners, the boards can be longer, and one can even be fashioned into a rudimentary handle.
You need at least a 3-board thickness to start. These boards are 1 1/2 inches thick, so that gives you a board that reduces your range of motion by 4.5 inches. I recommend also building a 4-board, and if you have long limbs, a 5-board.
There are many ways to use boards in your training. You can make one bench press or pushing day a board-only day, and either do a Westside Barbell style max effort day or work to any other number of variations, i.e. 5 x 5, 3 x 3, reverse pyramid, 10 x 3, etc. You can do these with or without a bench shirt. Alternatively, you can do them after your normal bench press workout as assistance.
Board presses can be done with various grips, from above and below your bench sticking point, and even in the power rack with the pins slightly below board height if you train alone. (For most lifters, training alone is usually a very bad idea on the bench press.
Vary your stances, range of motion, and grips.
Many athletes constantly search for the newest and most effective exercises to use in their training. Some of the best variations available are simple and come from changing your grip on the bar, your foot spacing, or the handle or implement you use to perform the movement.
For example, the bench press is a very different movement when done with a close grip, pinky on the ring, and even index finger outside the max legal bench press grip ring. In the squat, going to a wider or narrower stance changes the movement and what muscles it involves.
I'm aware of the theory that none of these changes effect muscle action, but move your squat stance in or out on your next workout and consider the theory yourself when you wake up and feel your legs the next day. In fact, DOMS (Delayed Onset Muscle Soreness) will peak for you at about noon to 2 PM the next day.
In the deadlift or bent row, your grip and stance can make a tremendous difference. If there's a big variation in your sumo and conventional deadlift, working the weaker style will bring up your strength and muscle mass.
Changing range of motion is another easy and effective variation. The board press changes the bench press range of motion, but the rack pull or deadlift off blocks can target a weak area also via adjusting range of motion. The squat can be targeted with low box to high.
If you have any questions, comments or concerns, feel free to reach out. I will do my best to fully inform you!