Polypropylene has long been the material makers say they want and then put off printing. It is light and tough, it shrugs off most chemicals, and it is everywhere in the moulded products around us. It also warps, it barely sticks to anything, and getting a first layer down can be painful. Filament specialist PPprint GmbH has built a toolkit around those problems, and its newest product, P-TPO 835 flex, reported by 3D Printing Industry, fills the soft end of that range. The new filament is a flexible polypropylene-based thermoplastic olefin (TPO), and the main reason it matters is that it is compatible with the company's existing PP grades.
A Range, Not a Single Spool
According to 3D Printing Industry, P-TPO 835 flex is the flexible member of a three-material polypropylene family. P-Filament 721 is the semi-flexible grade and the one most PPprint users will already know. Carbon 411 is the rigid, carbon-reinforced grade. P-TPO 835 flex is the soft one. PPprint says all three are compatible with one another.
That compatibility is the real news. Hybrid rigid-and-soft printing is not new in itself. Plenty of makers have printed TPU gaskets onto PLA or PETG housings with a second extruder or a filament swap. The trouble is that these are different polymer families, and the bond between them usually depends on mechanical interlocking or on the two materials happening to tolerate each other. Within one polymer family the situation changes. A part can move from rigid to semi-flexible to flexible while staying chemically polypropylene throughout, so the layers fuse as one material instead of acting as two.
The filament2print retailer listing says this directly: it describes P-TPO 835 flex as weldable to rigid PP for hybrid parts. That fits what the material is. The listing describes it as a TPO that combines polypropylene with a non-crosslinked elastomer. Because the elastomer is not crosslinked, the material remains a thermoplastic, and the listing describes it as recyclable.
What the Material Brings
Across the two sources, the property list is mostly what you would expect from polypropylene, now in a softer form. 3D Printing Industry lists low weight, chemical resistance, strong layer adhesion, recyclability, no water absorption, and suitability for sterilization. The retailer listing is more specific about chemicals, citing resistance to acids, bases and ozone. It also claims thermal stability up to 100°C.
The moisture claims stand out for anyone who has fought with flexible filaments. TPU is notoriously hygroscopic. Leave a spool out for a humid week and you get stringing, bubbles and a rough surface, so many makers simply keep their flexibles in a dry box all the time. 3D Printing Industry reports no water absorption for P-TPO 835 flex. The filament2print listing says low water absorption and says the material prints without prior drying. "Low" is probably the safer word to plan around, but either way this is a different maintenance job from TPU.
3D Printing Industry also says PPprint's product documentation identifies certified biological safety and skin-contact certification under DIN EN ISO 10993-5. That matters for wearables, grips, straps and anything else that will sit against a hand or wrist for hours. Makers aiming at medical or food-adjacent uses should still get the certification paperwork from the manufacturer and read exactly what it covers, rather than assuming it extends further than it does.
Printing It
PPprint's advice on hardware follows the familiar polypropylene approach. As reported by 3D Printing Industry, the company recommends its P-surface 141 build surface. PP is famous for refusing to stick to ordinary beds, and PPprint sells a dedicated build surface for exactly this reason. It also recommends P-support 279 for complex geometries that need supports and a direct-drive extruder. The direct-drive advice is no surprise for a flexible filament: a long Bowden tube gives soft filament room to buckle and compress between the drive gear and the hotend.
The filament2print listing gives a printing range of 200–240°C and offers the filament in both 1.75 mm and 2.85 mm diameters. The larger size will interest owners of 2.85 mm platforms, which often get left out of specialty launches. Colours are natural, beige and black.
On price, the listing shows EUR 58 for a 600 g spool of natural 1.75 mm filament, with volume discounts for multiple units. Stock varies by variant, and the page showed some combinations as temporarily out of stock, so check availability for the diameter and colour you want. The listing also advises using only low-friction PTFE-style tubes and avoiding systems that squeeze the filament.
How It Fits Against TPU
For background, 3D Printing Industry compares the launch with the TPU market, pointing to Recreus's Filaflex line, which spans Shore hardnesses from 60A to 95A. Its Filaflex 82A is cited at 650 percent elongation at break. That gives a sense of the competition: TPU is a mature, well-understood category with a wide spread of hardnesses and very high stretch at the soft end.
Neither source gives a Shore hardness or an elongation figure for P-TPO 835 flex, so a direct mechanical comparison is not possible yet. Makers who need a particular durometer, for a press-fit seal or a vibration damper for example, should wait for a datasheet or print test coupons before redesigning around it. In any case, the useful comparison is probably not "PP-TPO versus TPU" on stretch alone. TPU wins on range and familiarity. P-TPO 835 flex offers chemical resistance, low moisture sensitivity and, above all, a clean bond to rigid polypropylene, which TPU, being a different polymer family, is not designed to offer.
What It Means for Makers
The clearest use is the one the range was built for: single parts that need different stiffness in different places. Think of a rigid PP housing with a soft sealing lip. A carbon-reinforced bracket with a flexible strain-relief section. A chemical-resistant container with an integrated living hinge or soft gasket. A tool handle with a grippy overmould. Each of these is possible with a multi-material printer or a careful filament swap, and each benefits from all its sections being the same base polymer, both for the bond and for end-of-life recycling.
The barrier to entry is the usual polypropylene one. Without a suitable build surface, PP of any stiffness is a frustrating material, and buying into PPprint's ecosystem means buying its bed surface and possibly its support filament too. For makers already printing P-Filament 721 or carbon 411, the flexible grade is a natural addition. For everyone else, it is a stronger reason than before to take polypropylene seriously, as long as you accept that this is a system, not a single spool you can drop into any printer.
The open questions are the ones a datasheet will answer: hardness, elongation, and how well the weld holds up between grades under repeated flexing. Until those numbers appear, the sensible first step is a test print. Run a rigid-to-flex transition coupon, bend it until it fails, and see where it breaks.
