I struggled with what to make for invites when a Twitter friend suggested a message in a bottle. Okay, I could make this work. First step: Drink 10oz of bottled water for every invite you need to make. This can take a couple of days. Fair warning.
Step 1: Distress vellum for invite and name tag
~Wrinkle vellum - try not to tear it too much
~Using an ink pad, dab the re-flattened vellum - Don't be too perfect with this
(I used two different colors of ink - a dirty linen and a coffee stain color
~Spray vellum lightly with water
~Iron flat with a warm iron (no steam)
Step 2: Prepare burlap to be printed on (see this: Printing on burlap)
Step 3: Print invites & name tags on vellum; Jolly Roger on burlap
Step 4: Cut burlap to approx the width of the water bottle label. Rip vellum to give it a "rough" edge
Step 5: Glue Burlap around bottle (10oz water bottle from Walmart). I made sure to glue the skull opposite the manufacturer's stamp. I also didn't bother to remove the label, as the label provided a nice white backdrop when looking through the bottle.
Step 6: Use your favorite ribbon to thread through the name tag and around the top of the bottle (I removed the ring leftover from the cap)
Step 7: Add sand to bottle. I used about a 1/4 cup per. I also made sure to let the sand dry a bit.
Step 8: Roll up invite and shove it in the bottle.
These invites are best hand-delievered. If they must be mailed, "cork" the bottle - either with a real cork or the plastic bottle cap.
Invite wording (in the coolest ol' English font I could find)
Ye be invited
to join Captain Moose's crew
He'd like to celebrate
his fourth birthday with you
Chart yer course for [insert address here]
On [insert date here] at half past 10
Grub and Grog will be provided for ye treasure seekers
Deserters only 555x555x1234