Nested Condensation Coaster with Removable Basin Insert

What it's for

A two-part coaster for a glass or mug on a desk. The cup rests flat on the raised platform of the removable insert — nothing is inserted into a sleeve or ringed by walls — and condensation running down the glass collects in the basin around the platform. The outer shell is a second, watertight barrier that catches anything the insert lets past, and there are no drainage holes or outlets anywhere, so the water stays put until the insert is lifted out and emptied. The two parts print separately and can be cleaned separately.

• Outer Containment Shell — one continuous watertight body, open at the top so the inside is fully accessible with the insert out. Four integrated pillars support the insert.
• Inner Insert — raised cup platform, recessed collection basin, and a groove in the platform floor for a removable silicone grip ring.
• Support pillars — four 8 mm round pillars, 90° apart on a 58 mm radius, rising from the shell floor to hold the insert 3.5 mm clear of the bottom.
• Silicone provisions — a grip-ring groove in the recess floor and four pockets underneath the shell for non-slip feet. The silicone parts themselves are not printed.

Dimensions

• Outer shell: 148 mm diameter, 22 mm tall, 2.4 mm walls, 3 mm base.
• Inner insert: 141.8 mm diameter, 13.5 mm tall, sitting 3.5 mm above the shell floor with 0.7 mm clearance per side.
• Cup platform: 95 mm diameter, top surface at 19 mm height.
• Locating recess: 80 mm diameter, 1 mm deep, in the platform top.
• Grip-ring groove: 1.5 mm deep, between 34 and 37 mm radius, in the recess floor.
• Basin: about 24 mm wide and roughly 10.5 mm deep at the wall, holding approximately 55–65 ml before it overflows into the shell.
• Foot pockets: four at 10 mm, 1 mm deep, on a 58 mm radius circle, directly below the pillars.

Print notes

• Print both parts in PETG with four or more perimeters — the shell's wall seal is what keeps the desk dry.
• The shell's foot pockets stop short of the inside floor, so the base stays closed.
• Watch first-layer elephant foot on the shell's outer base edge; it can make the part rock.
• The shell rim stands 2 mm above the insert, and the space under the insert adds further secondary containment, so overflow is caught.
• The pillars print flat-bottomed with no supports, and the open gap under the insert allows inspection and drying after use.

Remix ideas

• Add a lift tab or finger notch to the insert rim — as it stands the tight gap means a wet insert may need a thumbnail or thin tool to lift, though the open underside helps.
• Add a small locating dimple to the insert underside to stop it sliding its 0.7 mm of play.
• Widen the platform for larger mugs; cups wider than 95 mm overhang the platform and drip into the basin, which works but is less stable.
• Increase the insert height or basin depth if you want more collection capacity.
• Swap the four-pocket foot pattern for a continuous silicone band if the coaster lives on a slippery surface.