The purpose of a Background is to anchor your character within the world, and allow you to interact with certain NPCs or factions in unique ways.
When creating a custom background or reflavoring an established background, you can choose two skill proficiencies and two tool proficiencies, swap around starting equipment, and reflavor the background feature however you like, so long as you run it by the DM.
Instead of two skill proficiencies, you may take one skill expertise. Instead of tool proficiencies, you can take proficiency in weapons, gaming sets, instruments, or learn languages.
If you want custom background equipment, you can start with 1 set of (nonmagical) clothes, 1 tool/gaming set/weapon, 1 container to keep things in, and 200 dollars worth of extra starting cash to spend on equipment.
Listed here are a few custom backgrounds that can be taken. This does not include unique backgrounds specifically for your characters, but it does give some insight into how I generally treat backgrounds.
Skill Proficiencies: Science, Nature
Tool Proficiencies: Mechanic's Tools, Air Vehicles
Equipment: Traveler's clothes, a medal, and a wallet containing $200
Even when you were young, you looked up to the stars in wonder. Your familiarity with them allows you to navigate on starry nights by the constellations alone, and so long as you know where you are, you know where the nearest route into space is. Additionally, other astronauts will recognize you and have commonalities with you.
Skill Proficiencies: Medicine, plus one from among Intimidation, Perception, or Persuasion
Tool Proficiencies: Alchemist's Supplies
Equipment: Common clothes, 5 doses of a common drug of your choice, and a wallet containing $150
In places of high and low society, you can always find someone to buy drugs from. Given access to a lab and a few minimal supplies, you can feed any drug addictions you and your companions have. When you spend time in someone’s presence, you can tell if they’re currently high on any common street drugs.
Skill Proficiencies: Insight, plus one from among either Persuasion or Deception
Languages: Two of your choice
Tool Proficiencies: Mechanic's Tools, Air Vehicles
Equipment: Fine clothes, an award from your company, and a wallet containing $250
You know how to speak with corporate employees, speaking to managers and wage slaves each in a manner befitting their station. You know how to communicate with corporate bureaucrats in an effective manner to get what you desire with minimal delay. When negotiating a transaction with a corporation, you can always at least get a fair market price.
Skill Proficiencies: Computer Use, Stealth
Tool Proficiencies: Hacking Tools, Forgery Kit
Equipment: Common clothes, hacking tools, explorer's pack, and a wallet containing $150
You are recognized as a member of an underground hacktivist organization. You have shared access to all their hacking programs and equipment, and you may be able to convince them to assist in hacking specific targets. You may also be called to assist in their hacktivist activities.
Your hacktivist group has some agenda that they want to see fulfilled, or some code which they act by. It could be a general political, economic, or societal agenda, or it could be a resistance against a very specific target. Work out what your hacktivist group's goals are with the DM.
Skill Proficiencies: Persuasion, Deception
Tool Proficiencies: Forgery Kit, Calligraphy Supplies
Equipment: Professional Suit, briefcase, 20 blank sheets of paper and a pen, a legal reference book, and a wallet containing $200
You are a legally operating lawyer, and are allowed to represent people in a court of of law. You are intimately familiar with the laws of your home region, and are able to research unfamiliar legal systems in half the time. You are bound to an ethics system to continue working as a lawyer, and if it is found that you violated the law or your code of ethics, you may be disbarred.
Skill Proficiencies: Science, Nature
Tool Proficiencies: Alchemist's Supplies, Glassblower's Tools
Equipment: Common clothes, lab coat, box of gloves, goggles, alchemist's supplies, and a wallet containing $150
You have written a doctoral thesis based on your research into one very specific branch of science. Choose a field of science: Physics, Chemistry, Biology, Computer Science, Robotics, Astronomy, Psychology, etc. Whenever you make a Science check related to your chosen field of study, you have Expertise on the check. If the science check is directly related to your thesis topic, your check is automatically treated as a natural 20. Work with the DM to determine what your thesis topic was.
Skill Proficiencies: Medicine, Science
Tool Proficiencies: Weaver's Tools, Herbalism Kit
Equipment: Common clothes, Lab coat, box of gloves, hand sanitizer, healer's kit, and a wallet containing $150
You have a medical doctorate, and are legally licensed to practice medicine in your home region. Over a short rest, you can sterilize a small room that is not overly dirty. When in a sterile environment, you have advantage on Medicine checks to perform surgery or to stabilize a creature.
You are licensed to perform medical operations for nonhumanoid creatures. You have advantage on Animal Handling checks to interact with creatures that are Bloodied, Injured, Poisoned, or Diseased, so long as you or your allies did not hurt them.
Skill Proficiencies: Stealth, Investigation
Tool Proficiencies: 2 of your choice
Equipment: Traveler's clothes, earpiece radio, one tool set of your choice, and a credstick with $200 on it
You come from a life of working as a covert mercenary, doing dirty work for various megacorporations while giving them plausible deniability. This experience has gotten you a few contacts within various megacorporations, as well as many among fellow shadowrunners. You have experience in infiltration, as well as staying undetected and off-the-grid, and know how to disappear when being hunted by law enforcement.
Skill Proficiencies: Choose two from among Deception, Persuasion, Perception, Sleight of Hand, Stealth, Survival
Tool Proficiencies: One type of Artisan's Tools
Equipment: Common clothes, a cheap employee-of-the-month award, a set of artisan's tools, and a wallet containing $100
You know the cheapest thrift stores, pawn shops, restaurants, and other stores where you can find discounts on everyday goods. You’re good at finding coupon codes and cut-rate prices for online shopping, event tickets, and public transportation. Additionally, you can make meals that can hold a person over even when resources are very limited, such as from a fridge containing only condiments.