Modular Seedling Tray, Parametric & Stackable

Transplant seedlings without the root shock: lift the insert and the whole root ball comes out intact, with no torn roots and no snapped stems.

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Each pot is two parts: a tapered shell and a removable insert. When a seedling is ready, you lift the insert straight up and the whole root ball comes with it, so the roots stay intact and the neighboring plants are never disturbed.

🌱 Why this tray

• Two-part pots: lift the insert to remove the root ball in one piece, with no digging and no torn roots.
• Fully parametric: generate any pot size and grid count from the customizer, one tray per size. The ready-to-print preset is a 3x3 tray for 60mm pots.
• Self-draining: the saucer is one watertight piece, and the grid bars use a pentagon (house-shaped) cross-section that sheds water to both sides instead of pooling on top.
• Mostly support-free: the inserts, grid bars, and saucer print with no supports on any FDM printer. Only the pot shells need light supports, for the small interior corner ledges.
• Stackable when empty: shells and inserts nest thanks to the 3° taper, so off-season storage stays compact.
• Use only the parts you need: the pots and inserts work on their own. The saucer and grid are optional, add them when you want a water tray and aligned rows.
• Label every seedling: write directly on the insert tab, or stick a label on it, so you always know what is growing where.
   

⚠️ Check the size before you print. The saucer prints in one piece. Depending on the pot size and the number of pots per row you pick in the customizer, the saucer can grow larger than your printer bed. Always check the saucer footprint against your bed before printing (see the bed-fit table further down). Need a tray bigger than your bed allows? Cut the saucer in Bambu Studio and join the pieces by gluing or with an interlocking joint.

🧠 Design decisions worth knowing

• L-feet at every corner raise each pot about 8mm above the saucer floor, so water circulates underneath and the pots never sit in a puddle.
• The grid does not carry the pots. They rest on their own feet on the floor; the half-lap grid only keeps them aligned, so nothing sags under the weight of wet soil.
• The saucer is a single piece, watertight by construction, with no glued seams to leak.
• The insert prints upright, holes down, for maximum rigidity in PETG, with a pinch handle at the top corner so it is easy to grip and lift.
   

🧩 What you print (5 parts)

• Pot shell (pot_shell): tapered square pot, open bottom, L-feet at the corners.
• Pot insert (pot_insert): L-shaped liner with concentric drainage holes and a pinch handle.
• Grid bar top (grid_bar_top) and grid bar bottom (grid_bar_bottom): straight bars that lock together with half-lap joints into a tic-tac-toe grid.
• Saucer (tray): one-piece watertight base; interior grooves hold the grid bar ends.
   

🖨️ Material: PETG recommended. It shrugs off moisture and UV, so the tray survives a full growing season outdoors.

💬 I am genuinely curious which parameters you find most useful, so tell me in the comments. Any adaptation you would like to see is very welcome, and so are photos of your own prints and setups.