Currently, we can only accept entries from the US, UK, Australia, Belgium, Canada (excluding Quebec), China, Colombia, Denmark, Germany, India, Netherlands, New Zealand, Norway, and Switzerland in our contests and challenges. Here's why, and what we're doing to expand.

(EDIT: while we're working on expanding the country list, here's our stop-gap program to reward great projects from international authors.  More info here.)

UPDATE 7/25/2012:
Colombia, Denmark, Germany, India, New Zealand, Norway, and Switzerland are now eligible for all contests!  We've updated the rules to make this clear.  More countries coming as fast as we can. --Christy

Broadly, there are two types of contests: games of skill and games of chance. Most of our contests are games of skill because they are judged, but we have occasionally run games of chance (random winner in a contest, random commenter wins a prize, etc..). Both types are regulated, sometimes stringently, across the world.

As an independent entity, we may have been violating the contest and gaming laws in every country on the planet except the US. While ignorance of the law isn't an acceptable reason to violate it, I did not spend the time to understand and comply with every country's contest laws. Without locations across the world, the potential for enforcement of laws I didn't know about was low.

We are now part of an international company, and the potential for enforcement is real.

Complying with laws is not a drag! It's what sustainable businesses that expect to be around for a long time do!

If you are upset about this, before you complain here, please write or call your representative, member of parliament, or dictator and ask them to simplify contest law in your country. The easier to understand your country's contest laws, the faster we can open our contests to you, and comply with your country's laws. Remember, obeying the law is what good websites do!

Autodesk is not trying to destroy the Instructables community by reducing the number of entrants to our contests; in fact, they're very concerned about the issue. We are trying to make sure we obey all the laws of all the countries where we operate. We are simultaneously working to understand the laws of more countries so we can legally run contests in more areas.

The terms and conditions of our contests are now in full compliance with the requirements of the US and Canada, except Quebec. Doing so required many hours of me talking to lawyers, and very large costs.

I have sorted the countries we will work on next by where our traffic comes from, and where past winners and entrants have come from. For reference:

Top 10 Countries by traffic:
US - open
UK - open
Canada - open (minus Quebec)
Australia - open
India - open
Germany - open
Philippines
Brazil
Mexico
France

Top 10 Countries by winners and entrants:
US - open
Canada - open
UK - open
Australia - open
Netherlands - open
Germany - open
New Zealand - open
Argentina
Colombia - open
India - open

The rules for games of skill and games of chance are drastically different. I foresee a situation where there are countries in which we can run one type of contest, but not the other.

Since we don't collect your country of residence during registration, our method of determining who is eligible is based on where a winner wants us to ship a prize.

Obeying laws is not a drag, but this is a tricky situation. I'll concede that you might view this as a bait and switch: we should have fully understood the contest laws of any country where we wanted to encourage DIY through our contests before allowing entrants from those countries. Instead, we allowed everyone, and now have to pause until I can talk to more lawyers. For that I apologize. Fixing this is one of our top priorities.  Even yesterday, I discussed how to get the UK and Australia added to the approved list, and we'll work from there.