I noticed that a lot of us try to sell components from our Instructables to other users, but there's not really a standardized way of doing so.
In my spare time, I created a site that allows us to do just that! You can see the featured post in the forum here, but I thought a nice how-to article might help, as well!
The marketplace is a third party site, but I think it is great because you can put the link to the items you're selling in your Instructables, browse other user's items, etc :)
Step 1: Setting Up Your Account
So the marketplace is located here:
It is a third party site, so you'll need to create an account. If you use the same username as you do on Instructables, it makes it easier for everyone!
Step 2: List Your Stuff!
It's really easy to list your items!
Remember, you can remove a listing from the "Account" tab.
Once you list your item, you can copy/paste the URL into your Instructable.
You can also distribute your "Seller" page so Instructable viewers can see all your items in one place :)
Step 3: Buy Something!
Just click "Buy" on any item! Click the seller's name to view all items by that seller. You can also browse by category.
Once you purchase an item, both you and the seller are notified via email and your email addresses and contact info are exchanged.
Step 4: Security, Etc
All payments are made directly through PayPal. In addition, email addresses are not exchanged until completion of a transaction.
The site has been tested, approved, and verified by PayPal! :)
Also, if you have any questions/feedback/ideas, let me know! I created the Marketplace for our community, so I'm happy to change/modify/update whatever you guys want! :)