It is a spherical 4R mechanism.Angle between center lines of revolute joints:
for the orange input shaft is γ = 10 deg.
for the blue output shaft is β = 90 deg.
for the green link is α = 90 deg.
Angle between input and output shafts is δ = γ = 10 deg.
Transmission ratio is 2. The output link revolves nearly regularly.
Velocity error is +/- 1.5% of average velocity. The smaller γ (δ = γ), the smaller error.
The mechanism has been created only on computer, needs to be verified in practice.