Vollmer Gmbh
Roundabout Fair Ride

Walthers Part # 770-3622, p. 586 Walthers 2010 HO Scale Reference
HO scale, $61.99, currently in stock at Walthers

 
You can build this colorful roundabout as a static model, or add motor #4200 (available separately) for a working ride,. 7-3/8 x 6-3/8 x 4-1/2" 18.5 x 16 x 11.2cm.