If any of you folks are interested in what I carry for my red team engagements:
NOTE: Entry tools are not legal everywhere. Before I go on an engagement, I make sure I know the relevant laws.
GoRuck GR1 - This bag is tough as nails, and big enough to carry all the gear I need. Whether I'm sneaking in late at night, crawling under fences, or talking my way into an office, I carry everything I need. It's not flashy, so it doesn't draw unwanted attention.
Important caveat: It has limited internal organization, so you need to buy additional pouches to keep your gear organized.
MacBook Pro - No red teamer is complete without a trusty laptop. The build quality of the MacBook is second to none, even though I don't know if I'll buy the newest model. I have a 13" rMBP. It's light, powerful enough to run my tools and a couple VMs, and solid enough that I know I won't break it. Also lasts for ~8 hours on battery; you never know if there will be a power outlet.
USB Rubber Ducky - Always take advantage of unlocked workstations. I take three with me on engagements; and set them up to deliver the appropriate payloads for the target environment.
Proxmark3 - Used to clone RFID badges. Can't break into an area? Clone an RFID badge and use that to get in. Not always cooperative, but always useful.
Anker PowerCore 20100 - Always have extra power for your phone or other mobile devices. The Anker PowerCore is up against the allowed limit for batteries you can take with you on an airplane, at 20,100 mAh. This will keep your devices charged for days.
Bash Bunny - Newly released, but incredibly useful. This is a very dangerous device, the big brother to the USB Rubber Ducky.
Alfa AWUS036NEH - The standard for wireless hacking. Cheap enough that you can afford to break one, and works with every OS out there.
WiFi Pineapple - A lot of people consider this a script kiddy tool, but it's very useful for real red teaming as well. Karma attacks, wireless sniffing, MitM capabilities... You can be dangerous with one of these.
Flash drives - You never know when you'll need to move files around. I keep at least 2x32GB flash drives with me.
External hard drive - Big enough to keep backups of my laptop if anything goes wrong. Never used for client data.
Under-door tool - Not a very well-known tool outside of the physical security space, but it's incredibly useful in most office environments. Gets you into practically any lever-handled door, locked or not.
Compressed air - If you think there will be doors with REX (request to exit) sensors, compressed air is a simple way to trick the sensor. Turn the can upside down, and spray a cloud of cold propellant to trick the sensor.
Snap gun - My picking skills aren't the greatest, but this makes up for that (somewhat). If I don't want to take the time to pick a lock, and I can afford a bit of noise, this is a quick way to pick certain locks.
Lockpicks - Lockpicks are sometimes necessary to get into a target facility. I'm no pro, but I always keep a set with me on engagements.
Notebook - Always be ready to write important details down, whether or not your laptop is out.
Flashlight - Always have a small, bright flashlight. When you're operating at night, you may need to see where you're going. Also helps if the power goes out.
T5557 RFID Cards - These cards allow you to emulate low-frequency RFID badges. These are what you write cloned badges to.
Mifare Chinese Magic Cards - Sometimes you'll come across an organization that makes use of high-frequency Mifare RFID badges. These cards are rewriteable Mifare cards that let you clone Mifare badges.
That's pretty much everything that I carry with me on my engagements; if I come up with something that I've forgotten, I'll be sure to add it in.