Terracotta or cast copper? Brick or cast bronze? Brick or cast brass?
Brush, polish, or patina and enjoy!
Introducing Copper Composite HTPLA.  Prints like plastic, but finishes like real metal for beautiful, durable parts from most standard 3D printers.  So many finishing possibilities, but here are some ideas to get you started (see sample Protognomes in product photos):
Heat treat your HTPLA print to survive harsher environments like the hot sun or a warm polishing wheel (more details below)
Wire Brush to expose metal for future oxidation or a bright, satin finish
Rock tumble with steel shot for darker, but smooth, shiny look
Paint part (black for example) to fill recesses with a contrasting color
Polish with a rotary tool, cotton buff, and polishing compound for a bright, mirror finish on high spots (darkens low spots)
Polish with paper for a clean, smooth, and bright finish with less darkening
Patina (oxidize) exposed metal naturally or accelerate with a 50/50 vinegar/hydrogen peroxide mixture saturated with salt. Place in sealed plastic bag to retain moisture. Heat further accelerates reaction.
Try these techniques separately or combine!  Change the order or try something new. If you discover a new technique, make something beautiful, or discover something unexpected, share it!  When you've got that perfect, WOW finish, consider preserving it with a clear coat or brush applicable water-based, food-safe, and dishwasher safe coating like Modge Podge. Practice your finishing a on a test piece like Protognome (download here).
 
Now the only question is, "What will you make?"
 
Heat treating beforehand to firm up HTPLA helps parts hold shape up to near melting (175C). Protect your investment in warm environments or push limits of application by exploring copper's thermal conductivity.  There is not enough copper to be electrically conductive, sintered, or plated, but there is a noticeable difference in weight and heat transfer.
 
Some application ideas include:
Faux brick or clay
Fixtures or hardware
Knobs or buttons
Heat sinks or exchangers
Fine art & sculpture
Emblems, signage, or trophies
Jewelry, like pendants or bracelets
Cosplay, game pieces, or figurines
Material data:
Base resin: HTPLA - Heat Treatable PLA
Additive: Real Copper/Bronze/Brass Powder
Particle size: less than 250 micron (0.25mm)
Odor: low or no
Density: Approx. 2.3 g/cc
Length (500g): 97m (1.75mm) and 36m (2.85mm)
Heat treating: 110C (225F) for 10 min or as required for desired result
Total loss of stiffness (before heat treat): 50-60C (Tg)
Total loss of stiffness (after heat treat): 150-175C (melting)
Dimension change (before heat treat): 0% X/Y/Z
Dimension change (after heat treat): 1.5% shrink X/Y and 1% growth Z typical but please calculate and confirm for your specific print and process
 
Printer settings:
 
Speed: 10-20 mm/s 1st layer, 20-80 mm/s rest of part
Nozzle Set-point: 185-215C (hottest on 1st layer for best adhesion)
Nozzle Actual: maintain set-point, reduce speed if less than 
Nozzle Type: Standard or wear resistant for extended use
Nozzle Diameter: 0.6mm or larger preferred, 0.4mm okay with 0.25mm minimum for experts
Layer thickness: 0.15-0.20mm recommended for a balance of quality, reliability, and productivity
Bed Temperature: Room-60C (over 60C can worsen warp)
Bed Preparation: Elmers purple disappearing glue stick or your other favorite PLA surface preparation
 
 
This material has been flow optimized and has less moisture uptake than standard PLAs, however composites are still sometimes more tricky to print depending on hardware and software settings.  The main challenge is to keep mass flow up (larger nozzle + fast speed) and in a single direction (minimal retraction) to avoid heat soak.  More on that topic here.