Ideas to make an outdoor pedestal that will cope with frost?

Wood, plastic, concrete, or metal will work. What are you placing on top? What is the specific frost issue?

What type of material are you using to build with?

Sorry should have said - Plinth/Pedestal is to hold Large concrete Weatherproof terracotta Vase in the Garden .

For a rustic look: a sturdy log planted upright. Be sure to use wood preservative to treat the wood closest to the ground. You could leave it rough or sand it smooth and seal with a high gloss polyurethane. Option 2: use native stacked stone. Depending on the stones you pick you may or may not need mortar to hold them together.

For a traditional look: make a mold for a precast cement pillar (reinforced with rebar and wire). You can use cement dye to set it apart from the cement Vase it supports. Or, check with your local granite fabricator. A polished pillar of granite could work too.

For an industrial look: use wrought iron such as used for porch corners. this might require some welding to join 2 corners together to create a pillar. Coat with a rust inhibitor. Paint or leave natural. Or use a traditional wrought iron table.

Check your local architectural salvage yard for something you like. Perhaps a part of an old Victorian lamp post would compliment your vase?