Downtime
Each player receives 40 hours of downtime each week. This downtime is per player rather than per character (so a player cannot create many different characters to gain more effective downtime). Players can use their downtime for crafting items, practicing professions, and retraining. Each day used for these purposes consumes 8 hours of downtime. Downtime that has not been used at the end of each week is lost.
Downtime is granted Monday of each real life week on the Discord server. Due to time zone differences and scheduling limits there is a 24 window from the time downtime hours are awarded to use any remaining downtime from the previous week before it is lost.
Craft and Profession
The campaign uses much revised Craft and Profession mechanics as described on the House Rules>Skills page.
Earning Money
Player characters may earn 1/2 their check result in a Craft or Profession skill each week in gold pieces without expending any downtime hours.
At the player's option they may expend downtime hours to gain a multiplier on the gold they gain from this use of the skills, up to a maximum of 40 hours per week. So a character who rolls a 20 profession check would get 10 gold pieces this week. The player could sacrifice 40 hours of downtime to increase it to 400 gold pieces (10 gp x 40 hours = 400 gp).
Characters may use the same mechanics with other practical skills. For example, a character could use Slight of Hand to perform carnival tricks or pick pockets, while another might use Knowledge skills to act as a sage or teacher at a school, and so on.
Only player characters benefit from expended downtime hours. NPCs (including cohorts, familiars, pets, psicrystals, followers, etc) are still assumed to make only 1/2 their check results each week.
Note: It may seem jarring that player characters can earn seemingly absurd amounts of money practicing normal professions (when the average cost of living is around 10-30 gp per month, earning hundreds of gold per week seems silly). However, this is an abstraction to compensate for the inability to spend time outside of adventuring.
In a traditional tabletop game players have the ability to pass time in a campaign for weeks, months, or even years between adventures (particularly in sandbox campaigns) but such is not very practical in a persistent world where many people are playing different adventures at different paces but are still able to regularly interact with one-another. Since that's not an option here players are allowed to spend their crafting time to represent working for weeks and months on end, but this has no tangible effect on the standards of the world (where it's assumed people still make only 1/2 their checks each week).
Trading
Players and their player characters can trade items with one-another as they see fit. Players are not only allowed to trade their items and services between one-another but they are encouraged to do so. Because money is rather limited and the GP limit of settlements in the campaign is 8,000 gp, "end game" items must be looted from adventures or crafted by players to become available. As such, players are encouraged to barter their time, money, and skills to other players for everyone's mutual benefit.
Trading is not limited to item creation. Players may also sell their services when applicable. Characters can act as mercenaries for other characters, or sell spellcasting services to them as well. The standard rate for spellcasting services according to the core rulebook is 10 gp x caster level x spell level, and so that sets the "going rate" of spells. However, spells above 6th level are very rare in the campaign so bartering those is more or less between the players involve as there is no real competition among the NPCs.
Ultimately, you are the master of your own time and skills. No one can force you to make items for you and vice versa. You are free to barter your time and services at any price you deem fit and others are free to do the same.