This is my first attempt at casting. I followed instructions from http://3dtopo.com/lostPLA/. I did not have any PLA so I used ABS.
• I made a 50%/50% mix of sand and plaster of paris.
• I submerged the object in the mix and vacuumed it down with a shop vac and a space bag.
• I waited for about 30 min for it to cure and removed them from the cups they were in. I did this so they could dry more.
• I then baked them in the oven at about 300°F for 4 hours.
• I then put them in the furnace to burn out the ABS
• I took out the warm molds and buried in sand.
• I melted down some scrap aluminum from around the yard and poured them into the molds.
(I did not have the crucibles hot enough at first so I had to do double pours. This is why they came out looking like they are 2 parts.)