Have a clear idea of your concept brought to reality.
Step 1: Know Your Site
Pay attention traffic flow for both people and cars moving past your site. Where will the best view of your project be? How does the Sun shine on or cast shadows onto your project? How will these conditions change during the day? Where is the wind coming from? Should you take special measures to protect your project?
Step 2: Workout the Details
Use sketches and 3D modeling to figure out how all the pieces will go together to
a) be buildable with the materials and tools you have available.
b) be moveable to and from the site.
Step 3: Create a Project Budget and Parts List
3D software can make this easy by working in duplicate, one model can be operating in parallel to your primary design model to act as a parts list.
Step 4: Supply Procurement
This will likely involve several locations, so keep things simple.
Step 5: Your Work Space
You may need several work spaces to perform different tasks and use different tools. Keep these constraints in mind when you begin working. This can severely undermine a project. Home shops, the TechShop, school resources and garages are all great options.
Step 6: PreBuilding to Get It Right
Take the time to build a 'dress rehearsal' of your prototype. This will undoubtedly uncover forgotten items, issues related construction, transport and design. It's time well spent.
Step 7: On-Site Set-up
Because a prototype is a short-term installation, setting up and breaking down should be kept as simple as possible. Building in modules is the best way to build as much as possible off-site and eases transport to your site.
Step 8: Express Your Concept
Designers often work so closely on a project that they forget how others might perceive a work for the first time, so special care should be given to graphics, signage, and instructions. To the degree all of the above can reinforce the design in an integrated way, the better.
Step 9: Make It Accessible!
Step 10: Have a Ball!
Don't just stay back and hope for the best. Get out there and interact with people. Sometimes all they need is a little nudge or a bit of permission and they will bring your visions to life.