You can make splines from plywood or solid stock.
How to attach two sheets of plywood.
Connections between two pieces of plywood vary depending on the purpose.
A butt block joint is made by edge gluing two pieces of plywood together and adding a backer block to one side of the seam.
The width of the butt block should be a minimum of 16 times the thickness of the plywood you are using.
Absolutely bopper simpson strong tie sheathing clips are used to join two pieces of sheathing at the edge.
To keep extra long pieces steady add an auxiliary fence.
According to the size of the wall you will have to cut the plywood to fit.
All you need to do is grab wood planks then lay it sideways along the wood pieces.
If you want to bond them together to make a single sheet of 8ftx2ft x 1 1 5 inch thick plywood you need to do this.
Next plane and saw the spline blank stock to match the width and combined depth of the grooves.
A wooden butt block joint provides a simple way to attach two adjoining pieces of plywood together.
This is considered the simplest method to connect the woods and the appearance is not highly important.
Next glue or nail the plank onto the surfaces of the wood pieces.
Well it depends on how you want to glue them and where you want to glue them.
Maybe explain a little more what the purpose is.
Plywood or metal strap.
Using a backer block to stop tear out cut kerfs on the ends to form a groove as wide as one third the thickness of your stock.
This 20 guage clip is for 3 4 inch sheathing as noted by the stamped 3 4 but they also make clips for other common plywood thickness.
First gather up some heavy objects say cinder blocks.
If your exterior plywood sheets are 4 feet wide for example a 10 foot wide wall will need 2 1 2 sheets.
Two pieces that meet at a right angle will use one type of joint and those that join end to end.
Step 2 line the plywood sheets against your wall.
I think frank has the solution four sheets of 3 8 plywood two running opposite to the other two.