Brick Rainbow MOC Tutorial: Build a 7-Color Gradient Arch
Bottom line first: a 60 cm-wide brick rainbow MOC takes about 1,200 bricks. At roughly 0.08 yuan per brick that works out to around 96 yuan, and a first-time builder can finish it in about 3 hours. The core technique is layering 1x2 arch bricks, with the seven colors — red, orange, yellow, green, cyan, blue and purple — each taking about 15% of the total parts so the gradient reads smoothly and evenly. The build breaks into three steps.
Step 1: Set the Size and Choose Your Bricks
Sketch the rainbow's span on the base first — a 60 x 24 cm baseplate is the recommended footprint. Stack eight 1x2 arch bricks into a single column to form the bottom layer, and leave three studs free at each foot as landing spots for the clouds. Where you can, pick smooth arch bricks with no studs on top. Budget about 170 bricks per color across the seven colors, then add 30 extra white ones for the clouds. That comes to a little over 1,200 pieces, so the budget stays under control.
Step 2: Lay the Seven-Color Gradient Arc
Start with red on the innermost edge. On each layer, add one extra stud at the apex of the curve so the arch opens up gradually. At every junction between two neighboring colors, interleave five transition bricks (orange-red, yellow-orange and so on) so the gradient doesn't break into visible bands. Press the assembly down by hand after every two layers to keep the arc face flat and smooth. Once all seven colors are laid, look at it from the side — it should read as a clean parabola. Level out any dips with 1x1 round bricks.
Step 3: Add Clouds and Finish
Stack three white arch bricks at each end of the rainbow to make a small cloud, and interlock 1x1 bricks in a cross pattern inside each cloud so it doesn't come apart. Finish by adding four reinforcement bars, 16 studs long, on the back. Stand the whole thing on its base and test how stable it is. When it's done, take photos from three different angles, and note the dimensions and parts list when you share it with the community.
FAQ
Q: How do I keep a brick rainbow MOC from sagging? A: The key is continuous interlocking of the arch bricks in the bottom layer, reinforced layer by layer. Press down every two layers and add four vertical reinforcement bars on the back. If the span goes past 80 cm, fit a base support — otherwise the middle tends to droop and deform.
Q: Can I build a rainbow with only one brick size? A: Yes, but 1x2 arch bricks alone make the curve too steep and the stud texture too obvious. Mix arch bricks with 1x1 round bricks and 2x2 curved plates; that makes the arc smoother without noticeably raising the total cost.
Q: How do I get a natural seven-color transition? A: Interleave five transition bricks at each junction between neighboring colors, and keep the arc-length difference between layers within one stud. For a finer result, split each of the seven colors into light, standard and dark shades — that makes the gradient about 40% more delicate.
Q: What does the whole parts run cost? A: At about 0.08 yuan per brick for domestic compatible bricks, 1,200 pieces is roughly 96 yuan. Add the baseplate and reinforcement parts and 110 yuan is the ceiling. If you use all brand-original bricks, expect about three times that, around 330 yuan.
Q: How is this different from a regular rainbow brick set? A: A set locks in the scene and the colors, while a MOC lets you change the span, the palette and the cloud shapes freely, and even add light bricks. You can download this set of plans at brickplan.cn and then adjust the gradient direction and the number of clouds to suit yourself.