Wheeled Glider

You need to purchase:

• Four free-turning furniture wheels (like the ones you find under plant rollers). Choose the wheels with the softest possible rubber finish, since hard wheels make your vehicle *loud*. They'll cost you about $4-8, depending on size and quality.
• Wood screws to attach the wheels. I used 5cm (2") long ones.
• Styrofoam insulation boards. If you do laminate with fiberglass, the classic, crumbly white stuff will do, but ideally you'll go for the much sturdier dense foam boards used for floor insulation. Depending on where you live, they may be pink, blue or green. In Europe you'll often encounter them under the brand name StyroDur. Go for the densest (heaviest / most stable) types you can find. You'll want enough material to model a seat on top of your base board. Expect to pay about $5-10 per board (60cm x 100cm x 6cm or so). Take the thickest boards available.
• Styrofoam glue. Note that regular glue contains solvents that will destroy foam board, so you must use special styrofoam glue (in Europe, try UHU Por).
• Aluminum tube (1" or 2.5cm diameter) for your handle bars.
• Optional: A piece of wood, maybe 1.5cm (roughly 1/2") thick, that will serve as a base for your vehicle.
• Optional: rubber bike handle covers for your handle bars. Makes the ride more comfortable and gives the vehicle a professional finish. These cost maybe $2.
• Optional: epoxy resin and hardener. You may want two different types: one resin for lamination (basically to stiffen the fiberglass cloth and bond it to the vehicle) and one for the surface finish (e.g. a resin with aluminum particles for a metal finish, but really any non-epoxy color or varnish is also fine, e.g. polyurethane boat varnish or even simple acrylic color).
• Optional: fiberglass cloth (or carbon fiber, but that's quite a bit more costly).  

Building instructions:

SIMPLE MODEL:

• This model will use only foam board and wheels, and is great for small children (<15kg / 30lbs) to ride on. Takes about 15-20 minutes to complete.

• Cut a base shape out of a 6cm thick foam board. You must use a high density board for this model or the wheels will not stay attached. If using StyroDur, this means you must use at least 4000CS, better 5000CS. 3035CS will not work - it's too soft.
• Screw (!) the wheels into the base plate near the four corners. Keep your wheels far enough apart to keep the vehicle stable, and keep the wheels a little bit away from the edge of the board so your child won't pinch a foot while riding.
• Then mount another piece of foam (probably a thicker board, or two glued together) vertically on top of the base and shape them into a comfortable seat. If you let the front and back parts rise about 10-15cm above the seat level, you can place the handle bars there for a comfortable ride.     
• Now stick your handle bars through the foam board you used as a seat to create a motor-cycle style setup. The easiest way to do this is to use a metal file to sharpen the outer (!) rim on one end of a piece of your handlebar tube into a kind of "drill", and then to work it through the foam board by simultaneously pushing and turning it. The sharpened edge will cut through the foam board rather easily but at the same time the hole will be just a little bit snug so your handle bars won't fall out. 
• Go!

MEDIUM MODEL:

• Same principle as the simple model, but using a wooden base plate to make the wheel attachment sturdier. Takes about 40 minutes to complete. Read the simple model instructions first, since they contain some tips not repeated here.
• Design a shape for your base plate. In general, dimensions should be at least: 60cm (25") long, 30cm (15") wide and 1.5cm (1/2") thick. A rectagular shape will do, but you may want rounded corners for that sleeker look (and to put less strin on your furniture in case of collisions :-)
• Glue a roughly pre-cut piece of foam board (maybe 6cm, 2.5" thick) onto the wooden base. For a good bond, make sure your surfaces a clean. Then liberally distribute your glue on both surfaces. Now spread the glue out (e.g. using another little piece of foam board as a tool) to get an even cover. Let the glue dry (about 5 mins). Now press the boards together *hard*. You won't be able to make any corrections once the surfaces tough, so align everything properly before you put them in contact.
• Cut the outline of the foam board to match the shape of your wooden base plate. You can do this using a knive, but the fastest method is to use a hot-wire saw. I'm using a simple Proxxon model. 
• Now build up a seat, either as described for the simple model (thick vertical foam boards) or by layering foam boards on top of the base foam board, cutting them into shape. The latter option allows you to really give the vehicle any shape you want, be it batmobile, tractor or locomotive. But it can be a lot of work (see professional model for details). You do not need to laminate the surface even of a shaped model (especially if you use the denser, sturdier foam types), but if you put in the work to make a nice shape, you may also want to give it a hard surface to protect it for future generations. ;-)
• Screw the wheels into the base plate.
• Go!

PROFESSIONAL MODEL: 

• Like the medium model, but with a shaped body and a fiberglass skin that basically makes it indestructible. Takes anywhere from 6 hours to 20 hours to complete (say 1 hour preparation, 4 hours shaping, 1 hour laminating plus whatever you want to invest into sanding and finishing...), depending on how perfect you want the surface.
• This version relies on tips in the simple and medium models that are not repeated, so please read those first.
• First, design a shape for your vehicle on paper. As you shape the body and get more familiar with the material, some aspects of the design may well change, so no need to have this perfect.
• Cut the wooden base board into the desired shape. In my final model I designed the base board around the wheels, with a circular area around each wheels axis that was large enough to extend about 1.5cm or 1/2" beyond the reach of the wheel (to avoid pinch points).
• File the bottom edge/rim of the wooden board to a rounded shape. This will allow the fiberglass cloth to reach around your bottom edge without detaching itself from the wood: the cloth does not like sharp edges.

• Build up layers of foam board above the wooden base, cutting them roughly to shape as you go. Make sure each layer is solidly glued to the one under it.

• Use whatever tools you have to shape your vehicle. I used a paper-cutter with a long, flexible steel blade to cut away larger blocks, then a rough and a fine file to do the detail shaping.

• When you have your final shape, use sand paper to achieve a somewhat regular finish. No need to be perfect here, since it'll all disappear under the fiberglass cloth, but the cloth and epoxy will stick better to a flat / smooth surface.

• You can also use a filler you'd use to smooth out cracks or holes in your walls to fill in any imperfections in the foam board, and to fill in edges where two boards meet (think rounded attachment edges for wings etc.).

• Now mix your epoxy resin and hardener as described in the instructions. Make sure to wear protective equipment (gloves, filter mask and goggles) as this stuff is nasty in many ways when not yet cured. You probably also want to read up on lamination techniques elsewhere on the web (search for fiberglass lamination on YouTube, for example), as all the details and tricks are beyond the scope of this article.
• Liberally apply epoxy to your vehicle. Lay on the fiberglass cloth. Wet it again with epoxy. You can cover your vehicle with as many patches and layers as you like, especially if you have complex shapes.

• Make sure the fiberglass cloth you buy has a "Koeper" weave; that way you can work it around amazingly varied surface shapes and still achieve excellent coverage. 
• You need to have your handlebar holes drilled before your lay on the fiberglass.
• Let the resin harden overnight. 
• Now apply whatever surface finish you may want. You'll definitely have to do quite a bit of sanding even if you do not put anything else on top of the fiberglass: you'll always have some nasty, extremely sharp and extremely hard fiberglass strands coming off the surface somewhere and you absolutely need to sand those off before you let your kid ride the vehicle!

 

 

• Screw in the wheels.
• Go!