Find a ruler (tool #1), but disregard its markings. You will not measure with it, just draw lines. Find a compass (tool #2) to draw circles. You will not use it to transfer distances or for measuring. Now you have all the tools that Euclid had to build an equilateral triangle.
Draw a segment of any desired length. Label its end points B and C, then place the tip of your compass at B and draw a circle with center at B and radius BC.
Then place the tip of your compass at C and draw a circle with center at C and radius BC.
Let A be the top intersection point of the two circles. Use your ruler to connect B to A and C to A.
Is triangle ABC equilateral?
Segments BC and BA are both radii of the same circle (with center at B), therefore are congruent:
BC ≡ BA
Segments CB and CA are also radii of the same circle (with center at C), and so they are congruent:
CB ≡ CA
In Euclid’s words “things which equal the same thing also equal one another,” and we have:
BC ≡ BA ≡ CA, and triangle ABC is equilateral.