These inexpensive lightweight 3D letters are a whopping 4 ft. tall! Made from plywood, roof flashing and strings of light bulbs, they will really turn heads for any weddings, event, or rumpus rooms.

Materials

4' x 8' x 3/32" (3,mm) plywood - approx half sheet per letter
1" x 2" x 8'-10' pine strips for the letter stiffening
1" x 4" x 8'-10' pine boards for the heart stiffening (due to the curves)
6" x 25' aluminum roof flashing
1' x 2'-3' x 7/32" (6mm) or thicker plywood for base
1" roofing nails
1.5" incandescent light string - 1-1.5 strings per letter
wood glue
wood screws for base
pop rivets
tie wraps
High resolution programmable dimmer for heart beating

Tools

hand jigsaw
table saw and dado blade - or hammer, handsaw and chisel for half-lap joints
hammer and chisel
power chopsaw - optional
sawhorse
drill with spade or forstner bits for bulb holes
7" x 24" x 1/8 scrap piece of steel for the bending anvil, length not critical

Step 1: Design of the Letters

I wanted a big blocky font with straight outside lines, fat serifs, and an interior space that would light up nicely from the bulbs. The font BlaxSlabXXL medium looked great so I downloaded it plus a pleasing heart clipart.

In the free program Inkscape:

Open a new page and resize it to 48" x 96" . Draw a 4" or 5" grid on a layer
Put individual text letters in 288 point size on a new layer. Convert to outline with Path->Object to Outline. Set fill to off. Set line width to 0.25" (6mm) and solid black.
Resize each letter to the full 48" height
Put dashed lines down the center of each letter stroke for the lights. I waited for the full size letter printout to lay out the position of the individual bulbs.
Put the heart on a layer and convert to outline as you did for the letters. Resize to full 48" height. Duplicate the heart, shrink and change stroke style to dashed and place it on the original heart for a dashed line for the lighting to follow.
Fit the large letters together on the full sheet to optimize. The 'J' and heart fit on one sheet, the 'W' needed it's own.
Save each letter and heart individually as a PDF

Run the free program PosteRazor:

Import the PDF file and print at full size on multiple sheets with 0.2" overlap.
Tape the sheets together and cut out.

Your paper patterns are ready to be traced on the plywood. They can be reused of course.

Step 2: Cutting Out Letters

Cut plywood

Lay out the paper patterns on the plywood, mark, and cut them out with a jigsaw.

Lay out lights

At this point, lay down poker chips or other bright markers to find a pleasing placement of the lights on the paper pattern and mark bulb locations. If the number of lights on the string don't exactly match, you can splice or trim light strings for 120V lights. Note: other types of light strings may not be cut or spliceable, check before you start hacking them up.

Drill the bulb holes now. Use a bit that lets the lamp base protrude just a little bit above the surface.

Back stiffening letters

To stiffen each letter, 1x2 pine strips are glued to the back. These are also what the aluminum flashing nails into.

Mark and cut the 1x2 pine around the perimeter so that they overlap at each junction. Run at least one 1x2s all the way from base to top or side to side to give rigidity. A base bracket needs to attach about 10"-12" up so plan a 1x2 for two of them to intercept.

Half-lap cut the 1x2 boards where they overlap so they all lie flat. I used a table saw with a dado cutter but a handsaw and chisel works fine.

Glue down all the 1x2 boards to the backs of the letters on a flat surface. Weigh down or clamp them to dry. You can work in sections if the half-lap joint is 'facing up' so think about that layout as you go.

Back stiffen heart

The curves on the heart are too hard to follow with 1x2 boards so I used 1x4 pine boards for stiffening with two 1x2 boards running horizontally. Trace the plywood edge back onto each 1x4 and jigsaw and sand it to follow the curves of the heart. This is how you can do letters that have more curves too. You can trim the inside of the board too if weight is a factor.

Each panel should be very light and rigid now.

Step 3: Paint the Letters

Paint the letters before putting on the edge flashing. Painting after is harder. Heart is heart color of course but the letters can match your theme colors!

Step 4: Form Edging

The aluminum flashing is wrapped around the edge of each letter for a full 3D effect, it reflects the light only in the interior and gives a really nice look.

The forming of this flashing takes 3 steps:

The front edge is folded over 180 degrees first for safe handling.
The flashing is bent around the outside of the letter
Nail it in place and pop rivet any seams.

Practice on a short piece of flashing first to refine your technique then measure around the perimeter of your letter/heart and find a nice seam point that uses 8' to 10' sections. Any longer are very hard to wrangle. Take into account the pieces will overlap a few inches.

Fold front edge 90 degrees first

Clamp the 1/8" steel sheet flat to a sawhorse or table with a clean edge slightly off the table. Lay the 8-10' x 6" piece of thin flashing on it extending on other tables or sawhorses flat. Gently straighten the flashing if it is still tightly coiled but it doesn't have to be perfectly flat, the next step will fix it.

Handle the flashing carefully to try not to dent or crease it unnecessarily. I used a 2"x2"x18" L angle steel in the photos but the sheet clamped to the sawhorse will work fine.

WITHOUT CUTTING YOURSELF, use a 1" spacer block of wood to hang the flashing evenly off the edge of the steel plate. Getting it very straight is important. Clamp the flashing on one or both ends if you like to keep it from slipping or just hold it down.

Gently, using the heel of your hand, fold the overhanging 1" of flashing down about 15 degrees down the length of the plate. Stop 6" before you get to the end so it isn't dented.

Go back down the length and press it down to about a 45 degree angle. Make sure it doesn't shift and you are getting a nice straight line. Don't bend all the way down the plate, let it be 15 degrees then 0 degrees.

Finally bend it to 90 degrees for about half the plate, leave the last part 45 then 0 still. Shift the flashing down 1/3. align with the block on the unbent portion and work the bend down the middle 1/3.

Step 5: Form Edging, Part 2

Fold front edge 180 degrees
Clamp the 1/8" steel plate vertically and as you worked the bend over in increments before, 45 degrees at a time now work the bend all of the way over it into a 'J' bend just as you did before working your way down the length. You should end with a nice tight wrap around the top edge of the 1/8" plate.

Lay the plate flat and rub the bend with a dowel or smooth screwdriver handle, slowly crimping it flatter and flatter without creasing until the fold is a tight flat 'J' bend. We need it flat so it will bend easily around the outside of the letters and heart.

Step 6: Wrapping the Letter With Flashing

Place a letter flat, face up on a very wide smooth surface and find an inconspicuous location for the first overlap. The sharp non-rolled edge goes right against the table all the way around.

Bending the flashing

Inside bends like the top of the heart need to be done away from the wood letter, outside bends like the bottom tip of the heart can be done right on the wood, so plan your bends and maybe practice marking a bend and then bending it on a scrap.

Inside bend

Use a carpenters square held tightly against the sharp bottom edge and bend it towards you with the palm of your hand, working it over to whatever angle you need. Test it against the letter, it should sit nicely without forcing it. If you need greater than 90 degrees, you can just bend it by hand farther since the crease line is established. You can lightly tap it with a hammer to get a nice sharp line.

Outside bend

This can be done right on the wood backing without marking. Lightly mark a straight line with a square and clamp two pieces of hardwood or metal at the mark. Bend as above until you get a nice sharp bend.

Attaching

After a whole piece is formed, tack it around the perimeter every 6" or so and 1" from each corner. If a new piece is continuing, bend it completely with a couple inch overlap. Trim the overlap to 1.5" before tacking it in place. Use a pop rivet to connect through the thicker 'J' bend and file or sand any sharp edges at the joints. If the bends are off or a measurement was bad, you can just cut out the bad part or remake it, the flashing is inexpensive.

Step 7: Adding Base and Lights

Base

Such a large letter needs a base that extends forward and back.

Cut 12" x 18-to-24" 7/32 plywood so it hides under the bottom flashing. Round the corners and sand it smooth. Screw the plywood squares to the 1x2 bases from underneath, 1" back from front edge of the flashing.

Add 45 degree braces to a 1x2 screwed to the back top of the plywood.The letter should be very stable now. These are so large that outdoors they might fly away in the wind.

For the heart, it ends in a point so add all of the bracing in picture 3 then paint the base flat black or a color that will match the floor.

Lights

I used strings of 1.5" cafe lights, 20 to a string. You can splice strings together if you just need a couple extra lights and you feel safe working with 120V electricity. They can usually be daisy chained for more. If you need fewer, you can cut the cord and electrical tape over the ends then shrink wrap the whole thing.

String all the lights and hot glue the cords to keep them in check. I notched the 1x2s for the cords so it could mount flat to the wall if desired. I cut small wood brackets and glued them to the letter backs, then tie-wrapped each light to the bracket to hold it perfectly in place.