Struggling with a concrete planter


I’m starting an urban design project based off my town centre and I have been modelling the main pedestrianised road. There is a small square with some curved concrete planters and it’s the main one that is really throwing me off, I have only done basic models in the past.

I’ve tried a few ways and also installed the Curvishear plug-in on Fredo tools which helped a lot but I don’t know how to create a smooth curve leading up to the top and back down again, without having a seam in the middle, or if there needs to be a boundary there, that it’s not a visible point where the two curves meet.

Would really appreciate any help/advice on how to make this work.
I have included a photo collage (new users can only put one photo) and a sketchup file. You can also find the location on Google maps at: 52.136742, -0.468619
Thank you!

Forum .skp (194.0 KB)
Sketchup.pdf (8.5 MB)

If the planter i symmetrical, you need only model half. I’d suggest drawing the planter at its full height (without the top course of stone). Make that a component. Then create a separate shape that has the curve you want on its bottom face. Move this shape into position, cut it, open the planter component, and go to Edit>paste in place. Then, with the planter component still open, select all the geometry, right-click, and choose Intersect Faces>With Selection. Erase all the parts you don’t want and you’ll be left with a planter that has a curved top. There is a plugin for positioning pieces along a path, but I’m blanking on the name.
Hope this helps.

That’s one of the hard bits.

I tried using the plugin SU Parametric Shapes from SketchUcation plugin store to make a Helical Ramp for the shape of the top.

Doesn’t quite work - looks like this when made according to your suggestion, using Intersect with Faces.

It’s humped in the middle.

So the shape isn’t just helical - it ‘flattens out’ at the top centre.

Looking at the photos, it isn’t a flat plane, either.

I wonder if a better approximation would be two shallow half cylinders, one ‘face up’ for the bottom half, and one face down for the top half?

I’ll try that and see what it looks like.

PS. Do you know the dimensions? None of them in your drawing are round numbers in either feet and inches, or in metres.

Well this isn’t the most graceful way to do it but good old fashioned Sandbox Tools can be used to create a sloped surface ‘from contours’…then you can 'Drape your planter outline (and interior) back onto the surface and remove the extra bits. I don’t have it installed but I’ll follow up with how to use Fredo’s ‘Joint Push Pull’ to do extrusions along a sloped surface.

Forum -ES.skp (127.7 KB)


I had a quick fiddle to very approximate shape/size. I used solid tools to Subtract a curved shape after the initial C shape Push/Pull. It requires more work for the actual planter of course, it’s a concept.


Well, it works, using two shallow part-cylinders. The shape looks good,

Can’t usefully go much further here without proper dimensions.

But by way of explanation I drew a plane down the centreline, wih two shallow opposite arcs

…then push pulled the upper shape to make a ‘cutter’ and moved into the context of the planter

Intersect Faces and then remove the excess, and reverse a few faces…

Hide the edges at the centre join, mirror it, and there you are.

I’m loving the number of responses and creativity in solutions here.

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Knowing your design requirements (and whether an accurate portrayal is needed) could be important. Some of these designs show a top cutting shape passing through the ramped walls. If however the wall in each part must be the same height as the adjacent wall, you have a classic curved ramp issue (what you’d use for a curved accessible ramp for example). In that case Fredo Curvishear and the Shape Bender plugins are possible solutions. Mihal’s solution seems to be based on this sort of shape.

Oh, I want to play too. How about Truebend? Depends on how exact you need the final product to be, might be hard to nail the real world dimensions to the mm this way, but it’s quick. I made a straight version using bezier curves, then bent the whole thing including lip details. Just a guess on the shape, I should have put more flat at the apex, but you get the idea.


My apologies for the bad measurements, I played around with it a lot and lost the initial design, the measurements are:

Length: 2400mm
Height: 700mm

Length: 2600mm
Height 700mm
The slope is slightly longer on this side.

The highest point is 1700mm and the lip around the outside is 500mm.
I’m trying to get something quite similar and yours is definitely looking a lot better than my attempts. Thanks!

Thank you so much for all your suggestions!
Regardless of this planter, you have shown me a lot of what SketchUp can do.

I’ll remember to post an image of the final thing

I’m going to use this method on a few other curved planters that are in the model, I was finding it hard to get the right shape, as they are tapered at one end.