You are going to build a wooden horse. It's an eye catcher as well as an attraction for the kids in your backyard.
The dimensions of the finished horse are as follows:

Sitting height: 70cm (~27.6 in)
Seat length: 58cm (~22.8 in)
Total height: 86cm (~33.9 in)Total Length: 100cm (~39.4 in)
Width: 34cm (~13.4 in)

You will need at least 20h working time depending on the tools available. Plus drying time for the paint the total build-up time will be one week or a little more. The measurements are metric, which means if you work in inches you may need to adopt some dimensions (divide by 2.54). I will point that out in the instructions.

Step 1: Tools and Materials

Tools:

Jigsaw or CNC Router (working space 1030 x 600 x 120 mm / 40.6 x 23.7 x 4.8 in)
Drilling machine and screwdriver
Sander and Wood Rasp
Hammer
Screw clamps
Drills
- Ø4mm Wood Drill (or according to screw diameter used for seat slats)
- Ø3mm Wood Drill (to pre-drill body)
- Ø9mm Wood Drill (for tail and mane holes)
- Ø10mm Wood and Metall Drill (or according to screw diameter for leg assembly)
Countersink
Wood filler (if needed)
Wood glue (optional, should also work without)

Materials:

3-Layer Wood Panel
- size 1030 x 600 mm
- width 28mm (or whatever is available)
- Type of wood: Spruce (better would be Larch, or what's available in your area)
Slats (or roof laths) (for seat)
- size 24 x 48 mm
- total length 9000mm ( equals in 15 single slats each 580mm long)
Squared timber (for legs)
- size 60x 60 mm
- total length 2000mm (equals in 4 legs each ~500mm long)
Wooden dowles Ø8mm (for fixture of the mane and tail)
Screws and nuts (best to use stainless steel)
- countersunk wood screw (Ø4mm x 60mm), 32 pieces
- lock screw M10 x 80 mm, 8 pieces
- nuts M10, 8 pieces
- washers for M10 screw, 16 pieces
Horse mane hair or equivalent
- You may ask a friendly owner of a horse with a rich horsetail to cut off a handful hairs (they regrow)
Paint
- Color according to your preferences
- Use paint available in your area
- Should be suitable for outdoors
- Recommended is PU acrylic paint (approx. 0.5L) as well as acrylic primer

Templates:

Attached you will find very helpful templates
Use pdf or svg for 2D printable templates
Use the FUSION files for working with 3D models on a CNC Router

Step 2: Head and Body

Jigsaw users

Print the template in original scale. See provided file "Head and Body PDFs"
It may be best to go to a copy shop where large plotters are available. Alternatively print on multiple standard size sheets.
Paste the template onto the 3-Layer Panel.

ATTENTION: If you use a panel with a thickness different than 28mm, you need to adopt the width of the cut-out on head and body elements.
The pockets for the legs are optional and designed for the use of a CNC Router. You can continue without them, if they appear to complicated.
Drill the Ø10mm holes according to template. Pre-drill with a smaller diameter if your material tends to break out.
Saw the Head and Body elements. Sand them afterwards until you are satisfied with the result.

CNC Router users

Download the 3D file suitable for FUSION360.
Prepare for milling on your machine. Use a Ø6mm end mill 2-flute, or similar.

ATTENTION: If you use a panel with a thickness different than 28mm, you need to adopt the width of the cut-out on the top of the body element.
Mill the Head and Body elements. Sand them afterwards until you are satisfied with the result.

Step 3: Body Slats and Legs

Please note: You may want to paint the uncut slats and square timber with a primer before cutting them to length. It's easier to handle instead of painting every single piece later on.

Body Slats:

Saw the slats to length (58cm). You need 15 pieces in total.
Use a chop saw if you have. The jigsaw will also do.
Drill holes Ø4mm (or according to screw diameter) to later fix the slats to the body.
Distance of the holes to the end side is ~2.2cm (may be adopted according to used material dimensions).
Countersink all holes on the top side.
Sand the edges nice and smooth. Round up the top side edges to make the sitting more comfortable.

Legs:

Saw the 4 legs to length (50cm).
Use the chop saw or jigsaw.
The holes will be drilled later on when legs get assembled to the body.
The recess of the legs is the trickiest part:

With chop saw
Set the cutting depth of the chop saw to 2-3cm.
Saw small grooves step by step (see picture)
Incline to saw blade to + or - 15° (depending on left or right leg).
Sand or rasp down all bumps left on the surface.
Break the small tongues left with a hammer.

With jigsaw
Works similar to the chop saw.
Mark the cutting depth on the side of the leg (see picture).
Incline the blade by + or - 15° (depending on left or right leg).
Alternatively mark the 15° angle on the leg and grind it or cut the corner off.

CNC Router
Use the attached 3D Model ("Leg Pair Recess Milling Operation".
The legs are milled in pairs (left and right).
Set the zero point according to picture attached.
If you use FUSION as CAM software use the "Parallel" 3D operation.
Clamp the legs according to picture attached.

Step 4: Paint

Prime and Sand:

It's not a must, but it's best to apply a primer to all parts first.
After primer has dried sand all parts with grit 120.

Paint:

Paint all parts with your preferred outdoor paint at least twice.
Sand between each layer with grit 320.
Let dry sufficiently.
Save some paint for little repairs after assembly.

Step 5: Assembly

Body and Head Elements:

Join Body elements with head.
Apply wood glue if you like.
Fix the body elements with a screw.

Legs:

Bring the legs into position onto the body elements.
Fix them with screw clamps.
Drill Ø10mm holes into the legs through the pre-drilled body wholes.
It's best to use a metall drill to avoid break outs.
Take the lock screws, washers and nuts to fix the legs to the body.

Body Slats:

Place the first slat on the top of the horse back and center it.
Pre-Drill the body element with a Ø3mm drill through the holes of the slat.
Fix the slat with 2 stainless screws.
The next slat is placed next to the first one with a distance of 1 to 2mm.
Use sheet metal or similar as a gauge to maintain constant distance.
Pre-drill again and fix the slat.

When all slats are fixed to the body elements, the horse looks already stunning.
In case you don't bother with a horsetail or mane, you are finished!

Step 6: Horsetail and Mane

Mane:

Bundle up a number of strands (see picture) for the mane
Drill Ø9mm holes into the back of the head.
Put strands into holes and hammer dowels Ø8mm inside. Apply some glue if you wish.
Paint over the dowels.

Horsetail:

Bundle up a strand of hairs for the tail
Fix the tail with a dowel just like the mane, only with a Ø10mm drilled hole if the strand is too strong.
Paint over the dowel at last.