With the resurgence of interest in '7:7 - A Dying Card Game', I've finally fixed a glaring typo (on Ser Marin of Kergus), and also am posting my guide for creating  your own cards. We've got our first official 3rd party content in the form of Updated card templates by Bruno Prosaiko, which could unleash the floodgates on your custom content! Here are some guidelines for creating your own cards:

• For Dungeon cards, higher Explore dice should come with riskier abilities.
• For Scum & Monster cards, consider these guidelines
  • 5s/HP, 10s per Armor Tier, 5s per Weapon Tier, round costs to the nearest 10s
  • Adjust Silver cost as you see fit dependent upon abilities
• For Equipment cards, use the price of similar equipment in Mork Borg as a guide.
  • Armor: -1~20s; -D2~40s; -D4~100s; -D6~150s
  • Weapon: D4~20s; D6~30s; D8~40s; D10~50s
  • These guidelines should be highly flexible based on card abilities.
  • Round costs to the nearest 10s, as with Scum & Monsters
• Likewise, Omen cards should be balanced against the existing Omen effects in Mork Bog.
• 7:7 isn't just Mork Borg themed, it's Mork Borg compatible. Consider the effect your Scum, Monsters, and Equipment might have as a ttrpg supplement. Dungeon cards are a bit more mechanistic, but can still be good inspiration for roleplaying campaigns.

If you do make any custom cards and post them here or elsewhere, drop a comment so I can add your work to the directory!